PaperMC/patches/server/0764-Highly-optimise-single-and-multi-AABB-VoxelShapes-an.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <spottedleaf@spottedleaf.dev>
Date: Mon, 4 May 2020 10:06:24 -0700
Subject: [PATCH] Highly optimise single and multi-AABB VoxelShapes and
 collisions


diff --git a/src/main/java/io/papermc/paper/util/CachedLists.java b/src/main/java/io/papermc/paper/util/CachedLists.java
index be668387f65a633c6ac497fca632a4767a1bf3a2..e08f4e39db4ee3fed62e37364d17dcc5c5683504 100644
--- a/src/main/java/io/papermc/paper/util/CachedLists.java
+++ b/src/main/java/io/papermc/paper/util/CachedLists.java
@@ -1,8 +1,57 @@
 package io.papermc.paper.util;
 
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.phys.AABB;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.util.UnsafeList;
+import java.util.List;
+
 public final class CachedLists {
 
-    public static void reset() {
+    // Paper start - optimise collisions
+    static final UnsafeList<AABB> TEMP_COLLISION_LIST = new UnsafeList<>(1024);
+    static boolean tempCollisionListInUse;
+
+    public static UnsafeList<AABB> getTempCollisionList() {
+        if (!Bukkit.isPrimaryThread() || tempCollisionListInUse) {
+            return new UnsafeList<>(16);
+        }
+        tempCollisionListInUse = true;
+        return TEMP_COLLISION_LIST;
+    }
+
+    public static void returnTempCollisionList(List<AABB> list) {
+        if (list != TEMP_COLLISION_LIST) {
+            return;
+        }
+        ((UnsafeList)list).setSize(0);
+        tempCollisionListInUse = false;
+    }
 
+    static final UnsafeList<Entity> TEMP_GET_ENTITIES_LIST = new UnsafeList<>(1024);
+    static boolean tempGetEntitiesListInUse;
+
+    public static UnsafeList<Entity> getTempGetEntitiesList() {
+        if (!Bukkit.isPrimaryThread() || tempGetEntitiesListInUse) {
+            return new UnsafeList<>(16);
+        }
+        tempGetEntitiesListInUse = true;
+        return TEMP_GET_ENTITIES_LIST;
+    }
+
+    public static void returnTempGetEntitiesList(List<Entity> list) {
+        if (list != TEMP_GET_ENTITIES_LIST) {
+            return;
+        }
+        ((UnsafeList)list).setSize(0);
+        tempGetEntitiesListInUse = false;
+    }
+    // Paper end - optimise collisions
+
+    public static void reset() {
+        // Paper start - optimise collisions
+        TEMP_COLLISION_LIST.completeReset();
+        TEMP_GET_ENTITIES_LIST.completeReset();
+        // Paper end - optimise collisions
     }
 }
diff --git a/src/main/java/io/papermc/paper/util/CollisionUtil.java b/src/main/java/io/papermc/paper/util/CollisionUtil.java
new file mode 100644
index 0000000000000000000000000000000000000000..98ca1199a823cdf55b913396ce0a24554e85f116
--- /dev/null
+++ b/src/main/java/io/papermc/paper/util/CollisionUtil.java
@@ -0,0 +1,645 @@
+package io.papermc.paper.util;
+
+import io.papermc.paper.voxel.AABBVoxelShape;
+import net.minecraft.core.BlockPos;
+import net.minecraft.server.level.ServerChunkCache;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.WorldGenRegion;
+import net.minecraft.util.Mth;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.item.Item;
+import net.minecraft.world.level.CollisionGetter;
+import net.minecraft.world.level.EntityGetter;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.border.WorldBorder;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.chunk.LevelChunkSection;
+import net.minecraft.world.level.material.FlowingFluid;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.phys.AABB;
+import net.minecraft.world.phys.Vec3;
+import net.minecraft.world.phys.shapes.ArrayVoxelShape;
+import net.minecraft.world.phys.shapes.CollisionContext;
+import net.minecraft.world.phys.shapes.EntityCollisionContext;
+import net.minecraft.world.phys.shapes.Shapes;
+import net.minecraft.world.phys.shapes.VoxelShape;
+import java.util.List;
+import java.util.Optional;
+import java.util.function.BiPredicate;
+import java.util.function.Predicate;
+
+public final class CollisionUtil {
+
+    public static final double COLLISION_EPSILON = 1.0E-7;
+
+    public static boolean isEmpty(final AABB aabb) {
+        return (aabb.maxX - aabb.minX) < COLLISION_EPSILON && (aabb.maxY - aabb.minY) < COLLISION_EPSILON && (aabb.maxZ - aabb.minZ) < COLLISION_EPSILON;
+    }
+
+    public static boolean isEmpty(final double minX, final double minY, final double minZ,
+                                  final double maxX, final double maxY, final double maxZ) {
+        return (maxX - minX) < COLLISION_EPSILON && (maxY - minY) < COLLISION_EPSILON && (maxZ - minZ) < COLLISION_EPSILON;
+    }
+
+    public static AABB getBoxForChunk(final int chunkX, final int chunkZ) {
+        double x = (double)(chunkX << 4);
+        double z = (double)(chunkZ << 4);
+        // use a bounding box bigger than the chunk to prevent entities from entering it on move
+        return new AABB(x - 3*COLLISION_EPSILON, Double.NEGATIVE_INFINITY, z - 3*COLLISION_EPSILON,
+            x + (16.0 + 3*COLLISION_EPSILON), Double.POSITIVE_INFINITY, z + (16.0 + 3*COLLISION_EPSILON), false);
+    }
+
+    /*
+      A couple of rules for VoxelShape collisions:
+      Two shapes only intersect if they are actually more than EPSILON units into each other. This also applies to movement
+      checks.
+      If the two shapes strictly collide, then the return value of a collide call will return a value in the opposite
+      direction of the source move. However, this value will not be greater in magnitude than EPSILON. Collision code
+      will automatically round it to 0.
+     */
+
+    public static boolean voxelShapeIntersect(final double minX1, final double minY1, final double minZ1, final double maxX1,
+                                              final double maxY1, final double maxZ1, final double minX2, final double minY2,
+                                              final double minZ2, final double maxX2, final double maxY2, final double maxZ2) {
+        return (minX1 - maxX2) < -COLLISION_EPSILON && (maxX1 - minX2) > COLLISION_EPSILON &&
+               (minY1 - maxY2) < -COLLISION_EPSILON && (maxY1 - minY2) > COLLISION_EPSILON &&
+               (minZ1 - maxZ2) < -COLLISION_EPSILON && (maxZ1 - minZ2) > COLLISION_EPSILON;
+    }
+
+    public static boolean voxelShapeIntersect(final AABB box, final double minX, final double minY, final double minZ,
+                                              final double maxX, final double maxY, final double maxZ) {
+        return (box.minX - maxX) < -COLLISION_EPSILON && (box.maxX - minX) > COLLISION_EPSILON &&
+               (box.minY - maxY) < -COLLISION_EPSILON && (box.maxY - minY) > COLLISION_EPSILON &&
+               (box.minZ - maxZ) < -COLLISION_EPSILON && (box.maxZ - minZ) > COLLISION_EPSILON;
+    }
+
+    public static boolean voxelShapeIntersect(final AABB box1, final AABB box2) {
+        return (box1.minX - box2.maxX) < -COLLISION_EPSILON && (box1.maxX - box2.minX) > COLLISION_EPSILON &&
+               (box1.minY - box2.maxY) < -COLLISION_EPSILON && (box1.maxY - box2.minY) > COLLISION_EPSILON &&
+               (box1.minZ - box2.maxZ) < -COLLISION_EPSILON && (box1.maxZ - box2.minZ) > COLLISION_EPSILON;
+    }
+
+    public static double collideX(final AABB target, final AABB source, final double source_move) {
+        if (source_move == 0.0) {
+            return 0.0;
+        }
+
+        if ((source.minY - target.maxY) < -COLLISION_EPSILON && (source.maxY - target.minY) > COLLISION_EPSILON &&
+            (source.minZ - target.maxZ) < -COLLISION_EPSILON && (source.maxZ - target.minZ) > COLLISION_EPSILON) {
+            if (source_move >= 0.0) {
+                final double max_move = target.minX - source.maxX; // < 0.0 if no strict collision
+                if (max_move < -COLLISION_EPSILON) {
+                    return source_move;
+                }
+                return Math.min(max_move, source_move);
+            } else {
+                final double max_move = target.maxX - source.minX; // > 0.0 if no strict collision
+                if (max_move > COLLISION_EPSILON) {
+                    return source_move;
+                }
+                return Math.max(max_move, source_move);
+            }
+        }
+        return source_move;
+    }
+
+    public static double collideY(final AABB target, final AABB source, final double source_move) {
+        if (source_move == 0.0) {
+            return 0.0;
+        }
+
+        if ((source.minX - target.maxX) < -COLLISION_EPSILON && (source.maxX - target.minX) > COLLISION_EPSILON &&
+            (source.minZ - target.maxZ) < -COLLISION_EPSILON && (source.maxZ - target.minZ) > COLLISION_EPSILON) {
+            if (source_move >= 0.0) {
+                final double max_move = target.minY - source.maxY; // < 0.0 if no strict collision
+                if (max_move < -COLLISION_EPSILON) {
+                    return source_move;
+                }
+                return Math.min(max_move, source_move);
+            } else {
+                final double max_move = target.maxY - source.minY; // > 0.0 if no strict collision
+                if (max_move > COLLISION_EPSILON) {
+                    return source_move;
+                }
+                return Math.max(max_move, source_move);
+            }
+        }
+        return source_move;
+    }
+
+    public static double collideZ(final AABB target, final AABB source, final double source_move) {
+        if (source_move == 0.0) {
+            return 0.0;
+        }
+
+        if ((source.minX - target.maxX) < -COLLISION_EPSILON && (source.maxX - target.minX) > COLLISION_EPSILON &&
+            (source.minY - target.maxY) < -COLLISION_EPSILON && (source.maxY - target.minY) > COLLISION_EPSILON) {
+            if (source_move >= 0.0) {
+                final double max_move = target.minZ - source.maxZ; // < 0.0 if no strict collision
+                if (max_move < -COLLISION_EPSILON) {
+                    return source_move;
+                }
+                return Math.min(max_move, source_move);
+            } else {
+                final double max_move = target.maxZ - source.minZ; // > 0.0 if no strict collision
+                if (max_move > COLLISION_EPSILON) {
+                    return source_move;
+                }
+                return Math.max(max_move, source_move);
+            }
+        }
+        return source_move;
+    }
+
+    public static AABB offsetX(final AABB box, final double dx) {
+        return new AABB(box.minX + dx, box.minY, box.minZ, box.maxX + dx, box.maxY, box.maxZ, false);
+    }
+
+    public static AABB offsetY(final AABB box, final double dy) {
+        return new AABB(box.minX, box.minY + dy, box.minZ, box.maxX, box.maxY + dy, box.maxZ, false);
+    }
+
+    public static AABB offsetZ(final AABB box, final double dz) {
+        return new AABB(box.minX, box.minY, box.minZ + dz, box.maxX, box.maxY, box.maxZ + dz, false);
+    }
+
+    public static AABB expandRight(final AABB box, final double dx) { // dx > 0.0
+        return new AABB(box.minX, box.minY, box.minZ, box.maxX + dx, box.maxY, box.maxZ, false);
+    }
+
+    public static AABB expandLeft(final AABB box, final double dx) { // dx < 0.0
+        return new AABB(box.minX - dx, box.minY, box.minZ, box.maxX, box.maxY, box.maxZ, false);
+    }
+
+    public static AABB expandUpwards(final AABB box, final double dy) { // dy > 0.0
+        return new AABB(box.minX, box.minY, box.minZ, box.maxX, box.maxY + dy, box.maxZ, false);
+    }
+
+    public static AABB expandDownwards(final AABB box, final double dy) { // dy < 0.0
+        return new AABB(box.minX, box.minY - dy, box.minZ, box.maxX, box.maxY, box.maxZ, false);
+    }
+
+    public static AABB expandForwards(final AABB box, final double dz) { // dz > 0.0
+        return new AABB(box.minX, box.minY, box.minZ, box.maxX, box.maxY, box.maxZ + dz, false);
+    }
+
+    public static AABB expandBackwards(final AABB box, final double dz) { // dz < 0.0
+        return new AABB(box.minX, box.minY, box.minZ - dz, box.maxX, box.maxY, box.maxZ, false);
+    }
+
+    public static AABB cutRight(final AABB box, final double dx) { // dx > 0.0
+        return new AABB(box.maxX, box.minY, box.minZ, box.maxX + dx, box.maxY, box.maxZ, false);
+    }
+
+    public static AABB cutLeft(final AABB box, final double dx) { // dx < 0.0
+        return new AABB(box.minX + dx, box.minY, box.minZ, box.minX, box.maxY, box.maxZ, false);
+    }
+
+    public static AABB cutUpwards(final AABB box, final double dy) { // dy > 0.0
+        return new AABB(box.minX, box.maxY, box.minZ, box.maxX, box.maxY + dy, box.maxZ, false);
+    }
+
+    public static AABB cutDownwards(final AABB box, final double dy) { // dy < 0.0
+        return new AABB(box.minX, box.minY + dy, box.minZ, box.maxX, box.minY, box.maxZ, false);
+    }
+
+    public static AABB cutForwards(final AABB box, final double dz) { // dz > 0.0
+        return new AABB(box.minX, box.minY, box.maxZ, box.maxX, box.maxY, box.maxZ + dz, false);
+    }
+
+    public static AABB cutBackwards(final AABB box, final double dz) { // dz < 0.0
+        return new AABB(box.minX, box.minY, box.minZ + dz, box.maxX, box.maxY, box.minZ, false);
+    }
+
+    public static double performCollisionsX(final AABB currentBoundingBox, double value, final List<AABB> potentialCollisions) {
+        for (int i = 0, len = potentialCollisions.size(); i < len; ++i) {
+            final AABB target = potentialCollisions.get(i);
+            value = collideX(target, currentBoundingBox, value);
+        }
+
+        return value;
+    }
+
+    public static double performCollisionsY(final AABB currentBoundingBox, double value, final List<AABB> potentialCollisions) {
+        for (int i = 0, len = potentialCollisions.size(); i < len; ++i) {
+            final AABB target = potentialCollisions.get(i);
+            value = collideY(target, currentBoundingBox, value);
+        }
+
+        return value;
+    }
+
+    public static double performCollisionsZ(final AABB currentBoundingBox, double value, final List<AABB> potentialCollisions) {
+        for (int i = 0, len = potentialCollisions.size(); i < len; ++i) {
+            final AABB target = potentialCollisions.get(i);
+            value = collideZ(target, currentBoundingBox, value);
+        }
+
+        return value;
+    }
+
+    public static Vec3 performCollisions(final Vec3 moveVector, AABB axisalignedbb, final List<AABB> potentialCollisions) {
+        double x = moveVector.x;
+        double y = moveVector.y;
+        double z = moveVector.z;
+
+        if (y != 0.0) {
+            y = performCollisionsY(axisalignedbb, y, potentialCollisions);
+            if (y != 0.0) {
+                axisalignedbb = offsetY(axisalignedbb, y);
+            }
+        }
+
+        final boolean xSmaller = Math.abs(x) < Math.abs(z);
+
+        if (xSmaller && z != 0.0) {
+            z = performCollisionsZ(axisalignedbb, z, potentialCollisions);
+            if (z != 0.0) {
+                axisalignedbb = offsetZ(axisalignedbb, z);
+            }
+        }
+
+        if (x != 0.0) {
+            x = performCollisionsX(axisalignedbb, x, potentialCollisions);
+            if (!xSmaller && x != 0.0) {
+                axisalignedbb = offsetX(axisalignedbb, x);
+            }
+        }
+
+        if (!xSmaller && z != 0.0) {
+            z = performCollisionsZ(axisalignedbb, z, potentialCollisions);
+        }
+
+        return new Vec3(x, y, z);
+    }
+
+    public static boolean addBoxesToIfIntersects(final VoxelShape shape, final AABB aabb, final List<AABB> list) {
+        if (shape instanceof AABBVoxelShape) {
+            final AABBVoxelShape shapeCasted = (AABBVoxelShape)shape;
+            if (voxelShapeIntersect(shapeCasted.aabb, aabb) && !isEmpty(shapeCasted.aabb)) {
+                list.add(shapeCasted.aabb);
+                return true;
+            }
+            return false;
+        } else if (shape instanceof ArrayVoxelShape) {
+            final ArrayVoxelShape shapeCasted = (ArrayVoxelShape)shape;
+            // this can be optimised by checking an "overall shape" first, but not needed
+
+            final double offX = shapeCasted.getOffsetX();
+            final double offY = shapeCasted.getOffsetY();
+            final double offZ = shapeCasted.getOffsetZ();
+
+            boolean ret = false;
+
+            for (final AABB boundingBox : shapeCasted.getBoundingBoxesRepresentation()) {
+                final double minX, minY, minZ, maxX, maxY, maxZ;
+                if (voxelShapeIntersect(aabb, minX = boundingBox.minX + offX, minY = boundingBox.minY + offY, minZ = boundingBox.minZ + offZ,
+                    maxX = boundingBox.maxX + offX, maxY = boundingBox.maxY + offY, maxZ = boundingBox.maxZ + offZ)
+                    && !isEmpty(minX, minY, minZ, maxX, maxY, maxZ)) {
+                    list.add(new AABB(minX, minY, minZ, maxX, maxY, maxZ, false));
+                    ret = true;
+                }
+            }
+
+            return ret;
+        } else {
+            final List<AABB> boxes = shape.toAabbs();
+
+            boolean ret = false;
+
+            for (int i = 0, len = boxes.size(); i < len; ++i) {
+                final AABB box = boxes.get(i);
+                if (voxelShapeIntersect(box, aabb) && !isEmpty(box)) {
+                    list.add(box);
+                    ret = true;
+                }
+            }
+
+            return ret;
+        }
+    }
+
+    public static void addBoxesTo(final VoxelShape shape, final List<AABB> list) {
+        if (shape instanceof AABBVoxelShape) {
+            final AABBVoxelShape shapeCasted = (AABBVoxelShape)shape;
+            if (!isEmpty(shapeCasted.aabb)) {
+                list.add(shapeCasted.aabb);
+            }
+        } else if (shape instanceof ArrayVoxelShape) {
+            final ArrayVoxelShape shapeCasted = (ArrayVoxelShape)shape;
+
+            final double offX = shapeCasted.getOffsetX();
+            final double offY = shapeCasted.getOffsetY();
+            final double offZ = shapeCasted.getOffsetZ();
+
+            for (final AABB boundingBox : shapeCasted.getBoundingBoxesRepresentation()) {
+                final AABB box = boundingBox.move(offX, offY, offZ);
+                if (!isEmpty(box)) {
+                    list.add(box);
+                }
+            }
+        } else {
+            final List<AABB> boxes = shape.toAabbs();
+            for (int i = 0, len = boxes.size(); i < len; ++i) {
+                final AABB box = boxes.get(i);
+                if (!isEmpty(box)) {
+                    list.add(box);
+                }
+            }
+        }
+    }
+
+    public static boolean isAlmostCollidingOnBorder(final WorldBorder worldborder, final AABB boundingBox) {
+        return isAlmostCollidingOnBorder(worldborder, boundingBox.minX, boundingBox.maxX, boundingBox.minZ, boundingBox.maxZ);
+    }
+
+    public static boolean isAlmostCollidingOnBorder(final WorldBorder worldborder, final double boxMinX, final double boxMaxX,
+                                                    final double boxMinZ, final double boxMaxZ) {
+        final double borderMinX = worldborder.getMinX(); // -X
+        final double borderMaxX = worldborder.getMaxX(); // +X
+
+        final double borderMinZ = worldborder.getMinZ(); // -Z
+        final double borderMaxZ = worldborder.getMaxZ(); // +Z
+
+        return
+            // Not intersecting if we're smaller
+            !voxelShapeIntersect(
+                boxMinX + COLLISION_EPSILON, Double.NEGATIVE_INFINITY, boxMinZ + COLLISION_EPSILON,
+                boxMaxX - COLLISION_EPSILON, Double.POSITIVE_INFINITY, boxMaxZ - COLLISION_EPSILON,
+                borderMinX, Double.NEGATIVE_INFINITY, borderMinZ, borderMaxX, Double.POSITIVE_INFINITY, borderMaxZ
+            )
+            &&
+
+            // Are intersecting if we're larger
+            voxelShapeIntersect(
+                boxMinX - COLLISION_EPSILON, Double.NEGATIVE_INFINITY, boxMinZ - COLLISION_EPSILON,
+                boxMaxX + COLLISION_EPSILON, Double.POSITIVE_INFINITY, boxMaxZ + COLLISION_EPSILON,
+                borderMinX, Double.NEGATIVE_INFINITY, borderMinZ, borderMaxX, Double.POSITIVE_INFINITY, borderMaxZ
+            );
+    }
+
+    public static boolean isCollidingWithBorderEdge(final WorldBorder worldborder, final AABB boundingBox) {
+        return isCollidingWithBorderEdge(worldborder, boundingBox.minX, boundingBox.maxX, boundingBox.minZ, boundingBox.maxZ);
+    }
+
+    public static boolean isCollidingWithBorderEdge(final WorldBorder worldborder, final double boxMinX, final double boxMaxX,
+                                                    final double boxMinZ, final double boxMaxZ) {
+        final double borderMinX = worldborder.getMinX() + COLLISION_EPSILON; // -X
+        final double borderMaxX = worldborder.getMaxX() - COLLISION_EPSILON; // +X
+
+        final double borderMinZ = worldborder.getMinZ() + COLLISION_EPSILON; // -Z
+        final double borderMaxZ = worldborder.getMaxZ() - COLLISION_EPSILON; // +Z
+
+        return boxMinX < borderMinX || boxMaxX > borderMaxX || boxMinZ < borderMinZ || boxMaxZ > borderMaxZ;
+    }
+
+    public static boolean getCollisionsForBlocksOrWorldBorder(final CollisionGetter getter, final Entity entity, final AABB aabb,
+                                                              final List<AABB> into, final boolean loadChunks, final boolean collidesWithUnloaded,
+                                                              final boolean checkBorder, final boolean checkOnly, final BiPredicate<BlockState, BlockPos> predicate) {
+        boolean ret = false;
+
+        if (checkBorder) {
+            if (CollisionUtil.isAlmostCollidingOnBorder(getter.getWorldBorder(), aabb)) {
+                if (checkOnly) {
+                    return true;
+                } else {
+                    CollisionUtil.addBoxesTo(getter.getWorldBorder().getCollisionShape(), into);
+                    ret = true;
+                }
+            }
+        }
+
+        int minBlockX = Mth.floor(aabb.minX - COLLISION_EPSILON) - 1;
+        int maxBlockX = Mth.floor(aabb.maxX + COLLISION_EPSILON) + 1;
+
+        int minBlockY = Mth.floor(aabb.minY - COLLISION_EPSILON) - 1;
+        int maxBlockY = Mth.floor(aabb.maxY + COLLISION_EPSILON) + 1;
+
+        int minBlockZ = Mth.floor(aabb.minZ - COLLISION_EPSILON) - 1;
+        int maxBlockZ = Mth.floor(aabb.maxZ + COLLISION_EPSILON) + 1;
+
+        final int minSection = WorldUtil.getMinSection(getter);
+        final int maxSection = WorldUtil.getMaxSection(getter);
+        final int minBlock = minSection << 4;
+        final int maxBlock = (maxSection << 4) | 15;
+
+        BlockPos.MutableBlockPos mutablePos = new BlockPos.MutableBlockPos();
+        CollisionContext collisionShape = null;
+
+        // special cases:
+        if (minBlockY > maxBlock || maxBlockY < minBlock) {
+            // no point in checking
+            return ret;
+        }
+
+        int minYIterate = Math.max(minBlock, minBlockY);
+        int maxYIterate = Math.min(maxBlock, maxBlockY);
+
+        int minChunkX = minBlockX >> 4;
+        int maxChunkX = maxBlockX >> 4;
+
+        int minChunkZ = minBlockZ >> 4;
+        int maxChunkZ = maxBlockZ >> 4;
+
+        ServerChunkCache chunkProvider;
+        if (getter instanceof WorldGenRegion) {
+            chunkProvider = null;
+        } else if (getter instanceof ServerLevel) {
+            chunkProvider = ((ServerLevel)getter).getChunkSource();
+        } else {
+            chunkProvider = null;
+        }
+        // TODO special case single chunk?
+
+        for (int currChunkZ = minChunkZ; currChunkZ <= maxChunkZ; ++currChunkZ) {
+            int minZ = currChunkZ == minChunkZ ? minBlockZ & 15 : 0; // coordinate in chunk
+            int maxZ = currChunkZ == maxChunkZ ? maxBlockZ & 15 : 15; // coordinate in chunk
+
+            for (int currChunkX = minChunkX; currChunkX <= maxChunkX; ++currChunkX) {
+                int minX = currChunkX == minChunkX ? minBlockX & 15 : 0; // coordinate in chunk
+                int maxX = currChunkX == maxChunkX ? maxBlockX & 15 : 15; // coordinate in chunk
+
+                int chunkXGlobalPos = currChunkX << 4;
+                int chunkZGlobalPos = currChunkZ << 4;
+                ChunkAccess chunk;
+                if (chunkProvider == null) {
+                    chunk = (ChunkAccess)getter.getChunkForCollisions(currChunkX, currChunkZ);
+                } else {
+                    chunk = loadChunks ? chunkProvider.getChunk(currChunkX, currChunkZ, true) : chunkProvider.getChunkAtIfLoadedImmediately(currChunkX, currChunkZ);
+                }
+
+
+                if (chunk == null) {
+                    if (collidesWithUnloaded) {
+                        if (checkOnly) {
+                            return true;
+                        } else {
+                            into.add(getBoxForChunk(currChunkX, currChunkZ));
+                            ret = true;
+                        }
+                    }
+                    continue;
+                }
+
+                LevelChunkSection[] sections = chunk.getSections();
+
+                // bound y
+
+                for (int currY = minYIterate; currY <= maxYIterate; ++currY) {
+                    LevelChunkSection section = sections[(currY >> 4) - minSection];
+                    if (section == null || section.isEmpty()) {
+                        // empty
+                        // skip to next section
+                        currY = (currY & ~(15)) + 15; // increment by 15: iterator loop increments by the extra one
+                        continue;
+                    }
+
+                    net.minecraft.world.level.chunk.PalettedContainer<BlockState> blocks = section.states;
+
+                    for (int currZ = minZ; currZ <= maxZ; ++currZ) {
+                        for (int currX = minX; currX <= maxX; ++currX) {
+                            int localBlockIndex = (currX) | (currZ << 4) | ((currY & 15) << 8);
+                            int blockX = currX | chunkXGlobalPos;
+                            int blockY = currY;
+                            int blockZ = currZ | chunkZGlobalPos;
+
+                            int edgeCount = ((blockX == minBlockX || blockX == maxBlockX) ? 1 : 0) +
+                                    ((blockY == minBlockY || blockY == maxBlockY) ? 1 : 0) +
+                                    ((blockZ == minBlockZ || blockZ == maxBlockZ) ? 1 : 0);
+                            if (edgeCount == 3) {
+                                continue;
+                            }
+
+                            BlockState blockData = blocks.get(localBlockIndex);
+                            if (blockData.isAir()) {
+                                continue;
+                            }
+
+                            if ((edgeCount != 1 || blockData.shapeExceedsCube()) && (edgeCount != 2 || blockData.getBlock() == Blocks.MOVING_PISTON)) {
+                                mutablePos.set(blockX, blockY, blockZ);
+                                if (collisionShape == null) {
+                                    collisionShape = new LazyEntityCollisionContext(entity);
+                                }
+                                VoxelShape voxelshape2 = blockData.getCollisionShape(getter, mutablePos, collisionShape);
+                                if (voxelshape2 != Shapes.empty()) {
+                                    VoxelShape voxelshape3 = voxelshape2.move((double)blockX, (double)blockY, (double)blockZ);
+
+                                    if (predicate != null && !predicate.test(blockData, mutablePos)) {
+                                        continue;
+                                    }
+
+                                    if (checkOnly) {
+                                        if (voxelshape3.intersects(aabb)) {
+                                            return true;
+                                        }
+                                    } else {
+                                        ret |= addBoxesToIfIntersects(voxelshape3, aabb, into);
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        return ret;
+    }
+
+    public static boolean getEntityHardCollisions(final CollisionGetter getter, final Entity entity, AABB aabb,
+                                                  final List<AABB> into, final boolean checkOnly, final Predicate<Entity> predicate) {
+        if (isEmpty(aabb) || !(getter instanceof EntityGetter entityGetter)) {
+            return false;
+        }
+
+        boolean ret = false;
+
+        // to comply with vanilla intersection rules, expand by -epsilon so we only get stuff we definitely collide with.
+        // Vanilla for hard collisions has this backwards, and they expand by +epsilon but this causes terrible problems
+        // specifically with boat collisions.
+        aabb = aabb.inflate(-COLLISION_EPSILON, -COLLISION_EPSILON, -COLLISION_EPSILON);
+        final List<Entity> entities = CachedLists.getTempGetEntitiesList();
+        try {
+            if (entity != null && entity.hardCollides()) {
+                entityGetter.getEntities(entity, aabb, predicate, entities);
+            } else {
+                entityGetter.getHardCollidingEntities(entity, aabb, predicate, entities);
+            }
+
+            for (int i = 0, len = entities.size(); i < len; ++i) {
+                final Entity otherEntity = entities.get(i);
+
+                if ((entity == null && otherEntity.canBeCollidedWith()) || (entity != null && entity.canCollideWith(otherEntity))) {
+                    if (checkOnly) {
+                        return true;
+                    } else {
+                        into.add(otherEntity.getBoundingBox());
+                        ret = true;
+                    }
+                }
+            }
+        } finally {
+            CachedLists.returnTempGetEntitiesList(entities);
+        }
+
+        return ret;
+    }
+
+    public static boolean getCollisions(final CollisionGetter view, final Entity entity, final AABB aabb,
+                                        final List<AABB> into, final boolean loadChunks, final boolean collidesWithUnloadedChunks,
+                                        final boolean checkBorder, final boolean checkOnly, final BiPredicate<BlockState, BlockPos> blockPredicate,
+                                        final Predicate<Entity> entityPredicate) {
+        if (checkOnly) {
+            return getCollisionsForBlocksOrWorldBorder(view, entity, aabb, into, loadChunks, collidesWithUnloadedChunks, checkBorder, checkOnly, blockPredicate)
+                || getEntityHardCollisions(view, entity, aabb, into, checkOnly, entityPredicate);
+        } else {
+            return getCollisionsForBlocksOrWorldBorder(view, entity, aabb, into, loadChunks, collidesWithUnloadedChunks, checkBorder, checkOnly, blockPredicate)
+                | getEntityHardCollisions(view, entity, aabb, into, checkOnly, entityPredicate);
+        }
+    }
+
+    public static final class LazyEntityCollisionContext extends EntityCollisionContext {
+
+        private CollisionContext delegate;
+        private final Entity entity;
+
+        public LazyEntityCollisionContext(final Entity entity) {
+            super(false, 0.0, null, null, null, Optional.ofNullable(entity));
+            this.entity = entity;
+        }
+
+        public CollisionContext getDelegate() {
+            return this.delegate == null ? this.delegate = (this.entity == null ? CollisionContext.empty() : CollisionContext.of(this.entity)) : this.delegate;
+        }
+
+        @Override
+        public boolean isDescending() {
+            return this.getDelegate().isDescending();
+        }
+
+        @Override
+        public boolean isAbove(final VoxelShape shape, final BlockPos pos, final boolean defaultValue) {
+            return this.getDelegate().isAbove(shape, pos, defaultValue);
+        }
+
+        @Override
+        public boolean hasItemOnFeet(final Item item) {
+            return this.getDelegate().hasItemOnFeet(item);
+        }
+
+        @Override
+        public boolean isHoldingItem(final Item item) {
+            return this.getDelegate().isHoldingItem(item);
+        }
+
+        @Override
+        public boolean canStandOnFluid(final FluidState state, final FlowingFluid fluid) {
+            return this.getDelegate().canStandOnFluid(state, fluid);
+        }
+    }
+
+    private CollisionUtil() {
+        throw new RuntimeException();
+    }
+}
diff --git a/src/main/java/io/papermc/paper/voxel/AABBVoxelShape.java b/src/main/java/io/papermc/paper/voxel/AABBVoxelShape.java
new file mode 100644
index 0000000000000000000000000000000000000000..d67a40e7be030142443680c89e1763fc9ecdfe0a
--- /dev/null
+++ b/src/main/java/io/papermc/paper/voxel/AABBVoxelShape.java
@@ -0,0 +1,200 @@
+package io.papermc.paper.voxel;
+
+import io.papermc.paper.util.CollisionUtil;
+import it.unimi.dsi.fastutil.doubles.DoubleArrayList;
+import it.unimi.dsi.fastutil.doubles.DoubleList;
+import net.minecraft.core.Direction;
+import net.minecraft.world.phys.AABB;
+import net.minecraft.world.phys.shapes.Shapes;
+import net.minecraft.world.phys.shapes.VoxelShape;
+import java.util.ArrayList;
+import java.util.List;
+
+public final class AABBVoxelShape extends VoxelShape {
+
+    public final AABB aabb;
+
+    public AABBVoxelShape(AABB aabb) {
+        super(Shapes.getFullUnoptimisedCube().shape);
+        this.aabb = aabb;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return CollisionUtil.isEmpty(this.aabb);
+    }
+
+    @Override
+    public double min(Direction.Axis enumdirection_enumaxis) {
+        switch (enumdirection_enumaxis.ordinal()) {
+            case 0:
+                return this.aabb.minX;
+            case 1:
+                return this.aabb.minY;
+            case 2:
+                return this.aabb.minZ;
+            default:
+                throw new IllegalStateException("Unknown axis requested");
+        }
+    }
+
+    @Override
+    public double max(Direction.Axis enumdirection_enumaxis) {
+        switch (enumdirection_enumaxis.ordinal()) {
+            case 0:
+                return this.aabb.maxX;
+            case 1:
+                return this.aabb.maxY;
+            case 2:
+                return this.aabb.maxZ;
+            default:
+                throw new IllegalStateException("Unknown axis requested");
+        }
+    }
+
+    @Override
+    public AABB bounds() {
+        return this.aabb;
+    }
+
+    // enum direction axis is from 0 -> 2, so we keep the lower bits for direction axis.
+    @Override
+    protected double get(Direction.Axis enumdirection_enumaxis, int i) {
+        switch (enumdirection_enumaxis.ordinal() | (i << 2)) {
+            case (0 | (0 << 2)):
+                return this.aabb.minX;
+            case (1 | (0 << 2)):
+                return this.aabb.minY;
+            case (2 | (0 << 2)):
+                return this.aabb.minZ;
+            case (0 | (1 << 2)):
+                return this.aabb.maxX;
+            case (1 | (1 << 2)):
+                return this.aabb.maxY;
+            case (2 | (1 << 2)):
+                return this.aabb.maxZ;
+            default:
+                throw new IllegalStateException("Unknown axis requested");
+        }
+    }
+
+    private DoubleList cachedListX;
+    private DoubleList cachedListY;
+    private DoubleList cachedListZ;
+
+    @Override
+    protected DoubleList getCoords(Direction.Axis enumdirection_enumaxis) {
+        switch (enumdirection_enumaxis.ordinal()) {
+            case 0:
+                return this.cachedListX == null ? this.cachedListX = DoubleArrayList.wrap(new double[] { this.aabb.minX, this.aabb.maxX }) : this.cachedListX;
+            case 1:
+                return this.cachedListY == null ? this.cachedListY = DoubleArrayList.wrap(new double[] { this.aabb.minY, this.aabb.maxY }) : this.cachedListY;
+            case 2:
+                return this.cachedListZ == null ? this.cachedListZ = DoubleArrayList.wrap(new double[] { this.aabb.minZ, this.aabb.maxZ }) : this.cachedListZ;
+            default:
+                throw new IllegalStateException("Unknown axis requested");
+        }
+    }
+
+    @Override
+    public VoxelShape move(double d0, double d1, double d2) {
+        return new AABBVoxelShape(this.aabb.move(d0, d1, d2));
+    }
+
+    @Override
+    public VoxelShape optimize() {
+        if (this.isEmpty()) {
+            return Shapes.empty();
+        } else if (this == Shapes.BLOCK_OPTIMISED || this.aabb.equals(Shapes.BLOCK_OPTIMISED.aabb)) {
+            return Shapes.BLOCK_OPTIMISED;
+        }
+        return this;
+    }
+
+    @Override
+    public void forAllBoxes(Shapes.DoubleLineConsumer voxelshapes_a) {
+        voxelshapes_a.consume(this.aabb.minX, this.aabb.minY, this.aabb.minZ, this.aabb.maxX, this.aabb.maxY, this.aabb.maxZ);
+    }
+
+    @Override
+    public List<AABB> toAabbs() { // getAABBs
+        List<AABB> ret = new ArrayList<>(1);
+        ret.add(this.aabb);
+        return ret;
+    }
+
+    @Override
+    protected int findIndex(Direction.Axis enumdirection_enumaxis, double d0) { // findPointIndexAfterOffset
+        switch (enumdirection_enumaxis.ordinal()) {
+            case 0:
+                return d0 < this.aabb.maxX ? (d0 < this.aabb.minX ? -1 : 0) : 1;
+            case 1:
+                return d0 < this.aabb.maxY ? (d0 < this.aabb.minY ? -1 : 0) : 1;
+            case 2:
+                return d0 < this.aabb.maxZ ? (d0 < this.aabb.minZ ? -1 : 0) : 1;
+            default:
+                throw new IllegalStateException("Unknown axis requested");
+        }
+    }
+
+    @Override
+    protected VoxelShape calculateFace(Direction direction) {
+        if (this.isEmpty()) {
+            return Shapes.empty();
+        }
+        if (this == Shapes.BLOCK_OPTIMISED) {
+            return this;
+        }
+        switch (direction) {
+            case EAST: // +X
+            case WEST: { // -X
+                final double from = direction == Direction.EAST ? 1.0 - CollisionUtil.COLLISION_EPSILON : CollisionUtil.COLLISION_EPSILON;
+                if (from > this.aabb.maxX || this.aabb.minX > from) {
+                    return Shapes.empty();
+                }
+                return new AABBVoxelShape(new AABB(0.0, this.aabb.minY, this.aabb.minZ, 1.0, this.aabb.maxY, this.aabb.maxZ)).optimize();
+            }
+            case UP: // +Y
+            case DOWN: { // -Y
+                final double from = direction == Direction.UP ? 1.0 - CollisionUtil.COLLISION_EPSILON : CollisionUtil.COLLISION_EPSILON;
+                if (from > this.aabb.maxY || this.aabb.minY > from) {
+                    return Shapes.empty();
+                }
+                return new AABBVoxelShape(new AABB(this.aabb.minX, 0.0, this.aabb.minZ, this.aabb.maxX, 1.0, this.aabb.maxZ)).optimize();
+            }
+            case SOUTH: // +Z
+            case NORTH: { // -Z
+                final double from = direction == Direction.SOUTH ? 1.0 - CollisionUtil.COLLISION_EPSILON : CollisionUtil.COLLISION_EPSILON;
+                if (from > this.aabb.maxZ || this.aabb.minZ > from) {
+                    return Shapes.empty();
+                }
+                return new AABBVoxelShape(new AABB(this.aabb.minX, this.aabb.minY, 0.0, this.aabb.maxX, this.aabb.maxY, 1.0)).optimize();
+            }
+            default: {
+                throw new IllegalStateException("Unknown axis requested");
+            }
+        }
+    }
+
+    @Override
+    public double collide(Direction.Axis enumdirection_enumaxis, AABB axisalignedbb, double d0) {
+        if (CollisionUtil.isEmpty(this.aabb) || CollisionUtil.isEmpty(axisalignedbb)) {
+            return d0;
+        }
+        switch (enumdirection_enumaxis.ordinal()) {
+            case 0:
+                return CollisionUtil.collideX(this.aabb, axisalignedbb, d0);
+            case 1:
+                return CollisionUtil.collideY(this.aabb, axisalignedbb, d0);
+            case 2:
+                return CollisionUtil.collideZ(this.aabb, axisalignedbb, d0);
+            default:
+                throw new IllegalStateException("Unknown axis requested");
+        }
+    }
+
+    @Override
+    public boolean intersects(AABB axisalingedbb) {
+        return CollisionUtil.voxelShapeIntersect(this.aabb, axisalingedbb);
+    }
+}
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index e40587b9c13d9170ef5dd0811e96b02ecaccebb2..52ffc39715def70a8ad3a99356be19bea5ef892b 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -419,7 +419,7 @@ public class ServerPlayer extends Player {
 
                 if (blockposition1 != null) {
                     this.moveTo(blockposition1, 0.0F, 0.0F);
-                    if (world.noCollision(this)) {
+                    if (world.noCollision(this, this.getBoundingBox(), null, true)) { // Paper - make sure this loads chunks, we default to NOT loading now
                         break;
                     }
                 }
@@ -427,7 +427,7 @@ public class ServerPlayer extends Player {
         } else {
             this.moveTo(blockposition, 0.0F, 0.0F);
 
-            while (!world.noCollision(this) && this.getY() < (double) (world.getMaxBuildHeight() - 1)) {
+            while (!world.noCollision(this, this.getBoundingBox(), null, true) && this.getY() < (double) (world.getMaxBuildHeight() - 1)) { // Paper - make sure this loads chunks, we default to NOT loading now
                 this.setPos(this.getX(), this.getY() + 1.0D, this.getZ());
             }
         }
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index cf8ed790e09987528178519ba99376f27b15245f..4c8f6d2d72194d313e7383b5a499c8ca1a84e1da 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -934,7 +934,7 @@ public abstract class PlayerList {
 
         worldserver1.getChunkSource().addRegionTicket(net.minecraft.server.level.TicketType.POST_TELEPORT, new net.minecraft.world.level.ChunkPos(location.getBlockX() >> 4, location.getBlockZ() >> 4), 1, entityplayer.getId()); // Paper
         entityplayer1.forceCheckHighPriority(); // Player - Chunk priority
-        while (avoidSuffocation && !worldserver1.noCollision(entityplayer1) && entityplayer1.getY() < (double) worldserver1.getMaxBuildHeight()) {
+        while (avoidSuffocation && !worldserver1.noCollision(entityplayer1, entityplayer1.getBoundingBox(), null, true) && entityplayer1.getY() < (double) worldserver1.getMaxBuildHeight()) { // Paper - make sure this loads chunks, we default to NOT loading now
             entityplayer1.setPos(entityplayer1.getX(), entityplayer1.getY() + 1.0D, entityplayer1.getZ());
         }
         // CraftBukkit start
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 74fcc1b45a9e57280da82f7c181530d4183872a5..481e84fda6dccfaf684c922a12fa19ed35c87b3c 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -1025,9 +1025,44 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, n
                 float f2 = this.getBlockSpeedFactor();
 
                 this.setDeltaMovement(this.getDeltaMovement().multiply((double) f2, 1.0D, (double) f2));
-                if (this.level.getBlockStatesIfLoaded(this.getBoundingBox().deflate(1.0E-6D)).noneMatch((iblockdata1) -> {
-                    return iblockdata1.is((Tag) BlockTags.FIRE) || iblockdata1.is(Blocks.LAVA);
-                })) {
+                // Paper start - remove expensive streams from here
+                boolean noneMatch = true;
+                AABB fireSearchBox = this.getBoundingBox().deflate(1.0E-6D);
+                {
+                    int minX = Mth.floor(fireSearchBox.minX);
+                    int minY = Mth.floor(fireSearchBox.minY);
+                    int minZ = Mth.floor(fireSearchBox.minZ);
+                    int maxX = Mth.floor(fireSearchBox.maxX);
+                    int maxY = Mth.floor(fireSearchBox.maxY);
+                    int maxZ = Mth.floor(fireSearchBox.maxZ);
+                    fire_search_loop:
+                    for (int fz = minZ; fz <= maxZ; ++fz) {
+                        for (int fx = minX; fx <= maxX; ++fx) {
+                            for (int fy = minY; fy <= maxY; ++fy) {
+                                net.minecraft.world.level.chunk.LevelChunk chunk = (net.minecraft.world.level.chunk.LevelChunk)this.level.getChunkIfLoadedImmediately(fx >> 4, fz >> 4);
+                                if (chunk == null) {
+                                    // Vanilla rets an empty stream if all the chunks are not loaded, so noneMatch will be true
+                                    // even if we're in lava/fire
+                                    noneMatch = true;
+                                    break fire_search_loop;
+                                }
+                                if (!noneMatch) {
+                                    // don't do get type, we already know we're in fire - we just need to check the chunks
+                                    // loaded state
+                                    continue;
+                                }
+
+                                BlockState type = chunk.getType(fx, fy, fz);
+                                if (type.is((Tag) BlockTags.FIRE) || type.is(Blocks.LAVA)) {
+                                    noneMatch = false;
+                                    // can't break, we need to retain vanilla behavior by ensuring ALL chunks are loaded
+                                }
+                            }
+                        }
+                    }
+                }
+                if (noneMatch) {
+                    // Paper end - remove expensive streams from here
                     if (this.remainingFireTicks <= 0) {
                         this.setRemainingFireTicks(-this.getFireImmuneTicks());
                     }
@@ -1149,39 +1184,79 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, n
         return offsetFactor;
     }
 
-    private Vec3 collide(Vec3 movement) {
-        AABB axisalignedbb = this.getBoundingBox();
-        CollisionContext voxelshapecollision = CollisionContext.of(this);
-        VoxelShape voxelshape = this.level.getWorldBorder().getCollisionShape();
-        Stream<VoxelShape> stream = !this.level.getWorldBorder().isWithinBounds(axisalignedbb) ? Stream.empty() : Stream.of(voxelshape); // Paper
-        Stream<VoxelShape> stream1 = this.level.getEntityCollisions(this, axisalignedbb.expandTowards(movement), (entity) -> {
-            return true;
-        });
-        RewindableStream<VoxelShape> streamaccumulator = new RewindableStream<>(Stream.concat(stream1, stream));
-        Vec3 vec3d1 = movement.lengthSqr() == 0.0D ? movement : Entity.collideBoundingBoxHeuristically(this, movement, axisalignedbb, this.level, voxelshapecollision, streamaccumulator);
-        boolean flag = movement.x != vec3d1.x;
-        boolean flag1 = movement.y != vec3d1.y;
-        boolean flag2 = movement.z != vec3d1.z;
-        boolean flag3 = this.onGround || flag1 && movement.y < 0.0D;
-
-        if (this.maxUpStep > 0.0F && flag3 && (flag || flag2)) {
-            Vec3 vec3d2 = Entity.collideBoundingBoxHeuristically(this, new Vec3(movement.x, (double) this.maxUpStep, movement.z), axisalignedbb, this.level, voxelshapecollision, streamaccumulator);
-            Vec3 vec3d3 = Entity.collideBoundingBoxHeuristically(this, new Vec3(0.0D, (double) this.maxUpStep, 0.0D), axisalignedbb.expandTowards(movement.x, 0.0D, movement.z), this.level, voxelshapecollision, streamaccumulator);
-
-            if (vec3d3.y < (double) this.maxUpStep) {
-                Vec3 vec3d4 = Entity.collideBoundingBoxHeuristically(this, new Vec3(movement.x, 0.0D, movement.z), axisalignedbb.move(vec3d3), this.level, voxelshapecollision, streamaccumulator).add(vec3d3);
-
-                if (vec3d4.horizontalDistanceSqr() > vec3d2.horizontalDistanceSqr()) {
-                    vec3d2 = vec3d4;
+    private Vec3 collide(Vec3 moveVector) {
+        // Paper start - optimise collisions
+        // This is a copy of vanilla's except that it uses strictly AABB math
+        if (moveVector.x == 0.0 && moveVector.y == 0.0 && moveVector.z == 0.0) {
+            return moveVector;
+        }
+
+        final Level world = this.level;
+        final AABB currBoundingBox = this.getBoundingBox();
+
+        if (io.papermc.paper.util.CollisionUtil.isEmpty(currBoundingBox)) {
+            return moveVector;
+        }
+
+        final List<AABB> potentialCollisions = io.papermc.paper.util.CachedLists.getTempCollisionList();
+        try {
+            final double stepHeight = (double)this.maxUpStep;
+            final AABB collisionBox;
+
+            if (moveVector.x == 0.0 && moveVector.z == 0.0 && moveVector.y != 0.0) {
+                if (moveVector.y > 0.0) {
+                    collisionBox = io.papermc.paper.util.CollisionUtil.cutUpwards(currBoundingBox, moveVector.y);
+                } else {
+                    collisionBox = io.papermc.paper.util.CollisionUtil.cutDownwards(currBoundingBox, moveVector.y);
+                }
+            } else {
+                if (stepHeight > 0.0 && (this.onGround || (moveVector.y < 0.0)) && (moveVector.x != 0.0 || moveVector.z != 0.0)) {
+                    // don't bother getting the collisions if we don't need them.
+                    if (moveVector.y <= 0.0) {
+                        collisionBox = io.papermc.paper.util.CollisionUtil.expandUpwards(currBoundingBox.expandTowards(moveVector.x, moveVector.y, moveVector.z), stepHeight);
+                    } else {
+                        collisionBox = currBoundingBox.expandTowards(moveVector.x, Math.max(stepHeight, moveVector.y), moveVector.z);
+                    }
+                } else {
+                    collisionBox = currBoundingBox.expandTowards(moveVector.x, moveVector.y, moveVector.z);
                 }
             }
 
-            if (vec3d2.horizontalDistanceSqr() > vec3d1.horizontalDistanceSqr()) {
-                return vec3d2.add(Entity.collideBoundingBoxHeuristically(this, new Vec3(0.0D, -vec3d2.y + movement.y, 0.0D), axisalignedbb.move(vec3d2), this.level, voxelshapecollision, streamaccumulator));
+            io.papermc.paper.util.CollisionUtil.getCollisions(world, this, collisionBox, potentialCollisions, false, true,
+                false, false, null, null);
+
+            if (io.papermc.paper.util.CollisionUtil.isCollidingWithBorderEdge(world.getWorldBorder(), collisionBox)) {
+                io.papermc.paper.util.CollisionUtil.addBoxesToIfIntersects(world.getWorldBorder().getCollisionShape(), collisionBox, potentialCollisions);
             }
-        }
 
-        return vec3d1;
+            final Vec3 limitedMoveVector = io.papermc.paper.util.CollisionUtil.performCollisions(moveVector, currBoundingBox, potentialCollisions);
+
+            if (stepHeight > 0.0
+                && (this.onGround || (limitedMoveVector.y != moveVector.y && moveVector.y < 0.0))
+                && (limitedMoveVector.x != moveVector.x || limitedMoveVector.z != moveVector.z)) {
+                Vec3 vec3d2 = io.papermc.paper.util.CollisionUtil.performCollisions(new Vec3(moveVector.x, stepHeight, moveVector.z), currBoundingBox, potentialCollisions);
+                final Vec3 vec3d3 = io.papermc.paper.util.CollisionUtil.performCollisions(new Vec3(0.0, stepHeight, 0.0), currBoundingBox.expandTowards(moveVector.x, 0.0, moveVector.z), potentialCollisions);
+
+                if (vec3d3.y < stepHeight) {
+                    final Vec3 vec3d4 = io.papermc.paper.util.CollisionUtil.performCollisions(new Vec3(moveVector.x, 0.0D, moveVector.z), currBoundingBox.move(vec3d3), potentialCollisions).add(vec3d3);
+
+                    if (vec3d4.horizontalDistanceSqr() > vec3d2.horizontalDistanceSqr()) {
+                        vec3d2 = vec3d4;
+                    }
+                }
+
+                if (vec3d2.horizontalDistanceSqr() > limitedMoveVector.horizontalDistanceSqr()) {
+                    return vec3d2.add(io.papermc.paper.util.CollisionUtil.performCollisions(new Vec3(0.0D, -vec3d2.y + moveVector.y, 0.0D), currBoundingBox.move(vec3d2), potentialCollisions));
+                }
+
+                return limitedMoveVector;
+            } else {
+                return limitedMoveVector;
+            }
+        } finally {
+            io.papermc.paper.util.CachedLists.returnTempCollisionList(potentialCollisions);
+        }
+        // Paper end - optimise collisions
     }
 
     public static Vec3 collideBoundingBoxHeuristically(@Nullable Entity entity, Vec3 movement, AABB entityBoundingBox, Level world, CollisionContext context, RewindableStream<VoxelShape> collisions) {
@@ -2320,9 +2395,12 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, n
             float f = this.dimensions.width * 0.8F;
             AABB axisalignedbb = AABB.ofSize(this.getEyePosition(), (double) f, 1.0E-6D, (double) f);
 
-            return this.level.getBlockCollisions(this, axisalignedbb, (iblockdata, blockposition) -> {
-                return iblockdata.isSuffocating(this.level, blockposition);
-            }).findAny().isPresent();
+            // Paper start
+            return io.papermc.paper.util.CollisionUtil.getCollisionsForBlocksOrWorldBorder(this.level, this, axisalignedbb, null,
+                false, false, false, true, (iblockdata, blockposition) -> {
+                    return iblockdata.isSuffocating(this.level, blockposition);
+            });
+            // Paper end
         }
     }
 
diff --git a/src/main/java/net/minecraft/world/level/CollisionGetter.java b/src/main/java/net/minecraft/world/level/CollisionGetter.java
index 2a784a8342e708e0813c7076a2ca8e429446ffd3..f38cd7e2c341ae2fbbe9dd26cf872da9571b416a 100644
--- a/src/main/java/net/minecraft/world/level/CollisionGetter.java
+++ b/src/main/java/net/minecraft/world/level/CollisionGetter.java
@@ -36,28 +36,40 @@ public interface CollisionGetter extends BlockGetter {
         return this.isUnobstructed(entity, Shapes.create(entity.getBoundingBox()));
     }
 
+    // Paper start - optimise collisions
+    default boolean noCollision(Entity entity, AABB box, Predicate<Entity> filter, boolean loadChunks) {
+        return !io.papermc.paper.util.CollisionUtil.getCollisionsForBlocksOrWorldBorder(this, entity, box, null, loadChunks, false, entity != null, true, null)
+            && !io.papermc.paper.util.CollisionUtil.getEntityHardCollisions(this, entity, box, null, true, filter);
+    }
+    // Paper end - optimise collisions
+
     default boolean noCollision(AABB box) {
-        return this.noCollision((Entity)null, box, (e) -> {
-            return true;
-        });
+        // Paper start - optimise collisions
+        return !io.papermc.paper.util.CollisionUtil.getCollisionsForBlocksOrWorldBorder(this, null, box, null, false, false, false, true, null)
+            && !io.papermc.paper.util.CollisionUtil.getEntityHardCollisions(this, null, box, null, true, null);
+        // Paper end - optimise collisions
     }
 
     default boolean noCollision(Entity entity) {
-        return this.noCollision(entity, entity.getBoundingBox(), (e) -> {
-            return true;
-        });
+        // Paper start - optimise collisions
+        AABB box = entity.getBoundingBox();
+        return !io.papermc.paper.util.CollisionUtil.getCollisionsForBlocksOrWorldBorder(this, entity, box, null, false, false, entity != null, true, null)
+            && !io.papermc.paper.util.CollisionUtil.getEntityHardCollisions(this, entity, box, null, true, null);
+        // Paper end - optimise collisions
     }
 
     default boolean noCollision(Entity entity, AABB box) {
-        return this.noCollision(entity, box, (e) -> {
-            return true;
-        });
+        // Paper start - optimise collisions
+        return !io.papermc.paper.util.CollisionUtil.getCollisionsForBlocksOrWorldBorder(this, entity, box, null, false, false, entity != null, true, null)
+            && !io.papermc.paper.util.CollisionUtil.getEntityHardCollisions(this, entity, box, null, true, null);
+        // Paper end - optimise collisions
     }
 
     default boolean noCollision(@Nullable Entity entity, AABB box, Predicate<Entity> filter) {
-        try { if (entity != null) entity.collisionLoadChunks = true; // Paper
-        return this.getCollisions(entity, box, filter).allMatch(VoxelShape::isEmpty);
-        } finally { if (entity != null) entity.collisionLoadChunks = false; } // Paper
+        // Paper start - optimise collisions
+        return !io.papermc.paper.util.CollisionUtil.getCollisionsForBlocksOrWorldBorder(this, entity, box, null, false, false, entity != null, true, null)
+            && !io.papermc.paper.util.CollisionUtil.getEntityHardCollisions(this, entity, box, null, true, filter);
+        // Paper end - optimise collisions
     }
 
     Stream<VoxelShape> getEntityCollisions(@Nullable Entity entity, AABB box, Predicate<Entity> predicate);
diff --git a/src/main/java/net/minecraft/world/level/CollisionSpliterator.java b/src/main/java/net/minecraft/world/level/CollisionSpliterator.java
index 6124e3a32325e8c74bf839010a79d7c82c49aaff..cffb08bcb63f7ee2d8a163d865d87a9031f19407 100644
--- a/src/main/java/net/minecraft/world/level/CollisionSpliterator.java
+++ b/src/main/java/net/minecraft/world/level/CollisionSpliterator.java
@@ -106,7 +106,7 @@ public class CollisionSpliterator extends AbstractSpliterator<VoxelShape> {
 
                 VoxelShape voxelShape = blockState.getCollisionShape(this.collisionGetter, this.pos, this.context);
                 if (voxelShape == Shapes.block()) {
-                    if (!this.box.intersects((double)i, (double)j, (double)k, (double)i + 1.0D, (double)j + 1.0D, (double)k + 1.0D)) {
+                    if (!io.papermc.paper.util.CollisionUtil.voxelShapeIntersect(this.box, (double)i, (double)j, (double)k, (double)i + 1.0D, (double)j + 1.0D, (double)k + 1.0D)) { // Paper - keep vanilla behavior for voxelshape intersection - See comment in CollisionUtil
                         continue;
                     }
 
diff --git a/src/main/java/net/minecraft/world/level/EntityGetter.java b/src/main/java/net/minecraft/world/level/EntityGetter.java
index 94130509e3a7980c378cc95c46821cf0fc753ce6..7224c56e8a68870364c6538c82c04f371b74aabd 100644
--- a/src/main/java/net/minecraft/world/level/EntityGetter.java
+++ b/src/main/java/net/minecraft/world/level/EntityGetter.java
@@ -49,7 +49,7 @@ public interface EntityGetter {
             return true;
         } else {
             for(Entity entity2 : this.getEntities(entity, shape.bounds())) {
-                if (!entity2.isRemoved() && entity2.blocksBuilding && (entity == null || !entity2.isPassengerOfSameVehicle(entity)) && Shapes.joinIsNotEmpty(shape, Shapes.create(entity2.getBoundingBox()), BooleanOp.AND)) {
+                if (!entity2.isRemoved() && entity2.blocksBuilding && (entity == null || !entity2.isPassengerOfSameVehicle(entity)) && shape.intersects(entity2.getBoundingBox())) { // Paper
                     return false;
                 }
             }
@@ -66,7 +66,7 @@ public interface EntityGetter {
         if (box.getSize() < 1.0E-7D) {
             return Stream.empty();
         } else {
-            AABB aABB = box.inflate(1.0E-7D);
+            AABB aABB = box.inflate(-1.0E-7D); // Paper - needs to be negated, or else we get things we don't collide with
             Predicate<Entity> hardCollides = (entityx) -> { // Paper - optimise entity hard collisions
                 if (true || entityx.getBoundingBox().intersects(aABB)) { // Paper - always true
                     if (entity == null) {
diff --git a/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java b/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java
index 4a7fdea6a5f966db444dc41f7215faa99e3820b3..d87f8d106834678364f8720447d671de60c2454e 100644
--- a/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java
+++ b/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java
@@ -685,7 +685,7 @@ public abstract class BlockBehaviour {
             }
             this.shapeExceedsCube = this.cache == null || this.cache.largeCollisionShape; // Paper - moved from actual method to here
             this.opacityIfCached = this.cache == null || this.isConditionallyFullOpaque() ? -1 : this.cache.lightBlock; // Paper - cache opacity for light
-
+            // TODO optimise light
         }
 
         public Block getBlock() {
diff --git a/src/main/java/net/minecraft/world/phys/AABB.java b/src/main/java/net/minecraft/world/phys/AABB.java
index 120498a39b7ca7aee9763084507508d4a1c425aa..68cc6f2a78a06293a29317fda72ab3ee79b3533a 100644
--- a/src/main/java/net/minecraft/world/phys/AABB.java
+++ b/src/main/java/net/minecraft/world/phys/AABB.java
@@ -25,6 +25,17 @@ public class AABB {
         this.maxZ = Math.max(z1, z2);
     }
 
+    // Paper start
+    public AABB(double minX, double minY, double minZ, double maxX, double maxY, double maxZ, boolean dummy) {
+        this.minX = minX;
+        this.minY = minY;
+        this.minZ = minZ;
+        this.maxX = maxX;
+        this.maxY = maxY;
+        this.maxZ = maxZ;
+    }
+    // Paper end
+
     public AABB(BlockPos pos) {
         this((double)pos.getX(), (double)pos.getY(), (double)pos.getZ(), (double)(pos.getX() + 1), (double)(pos.getY() + 1), (double)(pos.getZ() + 1));
     }
diff --git a/src/main/java/net/minecraft/world/phys/shapes/ArrayVoxelShape.java b/src/main/java/net/minecraft/world/phys/shapes/ArrayVoxelShape.java
index 99427b6130895ddecee8bcf77db72d809c24c375..61f5339042290eeaea54964cd3838d0bf4646cb2 100644
--- a/src/main/java/net/minecraft/world/phys/shapes/ArrayVoxelShape.java
+++ b/src/main/java/net/minecraft/world/phys/shapes/ArrayVoxelShape.java
@@ -6,6 +6,9 @@ import java.util.Arrays;
 import net.minecraft.Util;
 import net.minecraft.core.Direction;
 
+// Paper start
+import it.unimi.dsi.fastutil.doubles.AbstractDoubleList;
+// Paper end
 public class ArrayVoxelShape extends VoxelShape {
     private final DoubleList xs;
     private final DoubleList ys;
@@ -16,6 +19,11 @@ public class ArrayVoxelShape extends VoxelShape {
     }
 
     ArrayVoxelShape(DiscreteVoxelShape shape, DoubleList xPoints, DoubleList yPoints, DoubleList zPoints) {
+        // Paper start - optimise multi-aabb shapes
+        this(shape, xPoints, yPoints, zPoints, null, 0.0, 0.0, 0.0);
+    }
+    ArrayVoxelShape(DiscreteVoxelShape shape, DoubleList xPoints, DoubleList yPoints, DoubleList zPoints, net.minecraft.world.phys.AABB[] boundingBoxesRepresentation, double offsetX, double offsetY, double offsetZ) {
+        // Paper end - optimise multi-aabb shapes
         super(shape);
         int i = shape.getXSize() + 1;
         int j = shape.getYSize() + 1;
@@ -27,6 +35,12 @@ public class ArrayVoxelShape extends VoxelShape {
         } else {
             throw (IllegalArgumentException)Util.pauseInIde(new IllegalArgumentException("Lengths of point arrays must be consistent with the size of the VoxelShape."));
         }
+        // Paper start - optimise multi-aabb shapes
+        this.boundingBoxesRepresentation = boundingBoxesRepresentation == null ? this.toAabbs().toArray(EMPTY) : boundingBoxesRepresentation;
+        this.offsetX = offsetX;
+        this.offsetY = offsetY;
+        this.offsetZ = offsetZ;
+        // Paper end - optimise multi-aabb shapes
     }
 
     @Override
@@ -42,4 +56,152 @@ public class ArrayVoxelShape extends VoxelShape {
             throw new IllegalArgumentException();
         }
     }
+
+    // Paper start
+    public static final class DoubleListOffsetExposed extends AbstractDoubleList {
+
+        public final DoubleArrayList list;
+        public final double offset;
+
+        public DoubleListOffsetExposed(final DoubleArrayList list, final double offset) {
+            this.list = list;
+            this.offset = offset;
+        }
+
+        @Override
+        public double getDouble(final int index) {
+            return this.list.getDouble(index) + this.offset;
+        }
+
+        @Override
+        public int size() {
+            return this.list.size();
+        }
+    }
+
+    static final net.minecraft.world.phys.AABB[] EMPTY = new net.minecraft.world.phys.AABB[0];
+    final net.minecraft.world.phys.AABB[] boundingBoxesRepresentation;
+
+    final double offsetX;
+    final double offsetY;
+    final double offsetZ;
+
+    public final net.minecraft.world.phys.AABB[] getBoundingBoxesRepresentation() {
+        return this.boundingBoxesRepresentation;
+    }
+
+    public final double getOffsetX() {
+        return this.offsetX;
+    }
+
+    public final double getOffsetY() {
+        return this.offsetY;
+    }
+
+    public final double getOffsetZ() {
+        return this.offsetZ;
+    }
+
+    @Override
+    public java.util.List<net.minecraft.world.phys.AABB> toAabbs() {
+        if (this.boundingBoxesRepresentation == null) {
+            return super.toAabbs();
+        }
+        java.util.List<net.minecraft.world.phys.AABB> ret = new java.util.ArrayList<>(this.boundingBoxesRepresentation.length);
+
+        double offX = this.offsetX;
+        double offY = this.offsetY;
+        double offZ = this.offsetZ;
+
+        for (net.minecraft.world.phys.AABB boundingBox : this.boundingBoxesRepresentation) {
+            ret.add(boundingBox.move(offX, offY, offZ));
+        }
+
+        return ret;
+    }
+
+    protected static DoubleArrayList getList(DoubleList from) {
+        if (from instanceof DoubleArrayList) {
+            return (DoubleArrayList)from;
+        } else {
+            return DoubleArrayList.wrap(from.toDoubleArray());
+        }
+    }
+
+    @Override
+    public VoxelShape move(double x, double y, double z) {
+        if (x == 0.0 && y == 0.0 && z == 0.0) {
+            return this;
+        }
+        DoubleListOffsetExposed xPoints, yPoints, zPoints;
+        double offsetX, offsetY, offsetZ;
+
+        if (this.xs instanceof DoubleListOffsetExposed) {
+            xPoints = new DoubleListOffsetExposed(((DoubleListOffsetExposed)this.xs).list, offsetX = this.offsetX + x);
+            yPoints = new DoubleListOffsetExposed(((DoubleListOffsetExposed)this.ys).list, offsetY = this.offsetY + y);
+            zPoints = new DoubleListOffsetExposed(((DoubleListOffsetExposed)this.zs).list, offsetZ = this.offsetZ + z);
+        } else {
+            xPoints = new DoubleListOffsetExposed(getList(this.xs), offsetX = x);
+            yPoints = new DoubleListOffsetExposed(getList(this.ys), offsetY = y);
+            zPoints = new DoubleListOffsetExposed(getList(this.zs), offsetZ = z);
+        }
+
+        return new ArrayVoxelShape(this.shape, xPoints, yPoints, zPoints, this.boundingBoxesRepresentation, offsetX, offsetY, offsetZ);
+    }
+
+    @Override
+    public final boolean intersects(net.minecraft.world.phys.AABB axisalingedbb) {
+        // this can be optimised by checking an "overall shape" first, but not needed
+        double offX = this.offsetX;
+        double offY = this.offsetY;
+        double offZ = this.offsetZ;
+
+        for (net.minecraft.world.phys.AABB boundingBox : this.boundingBoxesRepresentation) {
+            if (io.papermc.paper.util.CollisionUtil.voxelShapeIntersect(axisalingedbb, boundingBox.minX + offX, boundingBox.minY + offY, boundingBox.minZ + offZ,
+                    boundingBox.maxX + offX, boundingBox.maxY + offY, boundingBox.maxZ + offZ)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    @Override
+    public void forAllBoxes(Shapes.DoubleLineConsumer doubleLineConsumer) {
+        if (this.boundingBoxesRepresentation == null) {
+            super.forAllBoxes(doubleLineConsumer);
+            return;
+        }
+        for (final net.minecraft.world.phys.AABB boundingBox : this.boundingBoxesRepresentation) {
+            doubleLineConsumer.consume(boundingBox.minX + this.offsetX, boundingBox.minY + this.offsetY, boundingBox.minZ + this.offsetZ,
+                boundingBox.maxX + this.offsetX, boundingBox.maxY + this.offsetY, boundingBox.maxZ + this.offsetZ);
+        }
+    }
+
+    @Override
+    public VoxelShape optimize() {
+        if (this == Shapes.empty() || this.boundingBoxesRepresentation.length == 0) {
+            return this;
+        }
+
+        VoxelShape simplified = Shapes.empty();
+        for (final net.minecraft.world.phys.AABB boundingBox : this.boundingBoxesRepresentation) {
+            simplified = Shapes.joinUnoptimized(simplified, Shapes.box(boundingBox.minX + this.offsetX, boundingBox.minY + this.offsetY, boundingBox.minZ + this.offsetZ,
+                    boundingBox.maxX + this.offsetX, boundingBox.maxY + this.offsetY, boundingBox.maxZ + this.offsetZ), BooleanOp.OR);
+        }
+
+        if (!(simplified instanceof ArrayVoxelShape)) {
+            return simplified;
+        }
+
+        final net.minecraft.world.phys.AABB[] boundingBoxesRepresentation = ((ArrayVoxelShape)simplified).getBoundingBoxesRepresentation();
+
+        if (boundingBoxesRepresentation.length == 1) {
+            return new io.papermc.paper.voxel.AABBVoxelShape(boundingBoxesRepresentation[0]).optimize();
+        }
+
+        return simplified;
+    }
+    // Paper end
+
 }
diff --git a/src/main/java/net/minecraft/world/phys/shapes/Shapes.java b/src/main/java/net/minecraft/world/phys/shapes/Shapes.java
index 16bc18cacbf7a23fb744c8a12e7fd8da699b2fea..2fb416bd1d7a9879c13907b7e3c6b857fb1bf0ed 100644
--- a/src/main/java/net/minecraft/world/phys/shapes/Shapes.java
+++ b/src/main/java/net/minecraft/world/phys/shapes/Shapes.java
@@ -26,16 +26,17 @@ public final class Shapes {
         DiscreteVoxelShape discreteVoxelShape = new BitSetDiscreteVoxelShape(1, 1, 1);
         discreteVoxelShape.fill(0, 0, 0);
         return new CubeVoxelShape(discreteVoxelShape);
-    });
+    }); public static VoxelShape getFullUnoptimisedCube() { return BLOCK; } // Paper - OBFHELPER
     public static final VoxelShape INFINITY = box(Double.NEGATIVE_INFINITY, Double.NEGATIVE_INFINITY, Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY);
     private static final VoxelShape EMPTY = new ArrayVoxelShape(new BitSetDiscreteVoxelShape(0, 0, 0), (DoubleList)(new DoubleArrayList(new double[]{0.0D})), (DoubleList)(new DoubleArrayList(new double[]{0.0D})), (DoubleList)(new DoubleArrayList(new double[]{0.0D})));
+    public static final io.papermc.paper.voxel.AABBVoxelShape BLOCK_OPTIMISED = new io.papermc.paper.voxel.AABBVoxelShape(new AABB(0.0, 0.0, 0.0, 1.0, 1.0, 1.0)); // Paper
 
     public static VoxelShape empty() {
         return EMPTY;
     }
 
     public static VoxelShape block() {
-        return BLOCK;
+        return BLOCK_OPTIMISED; // Paper
     }
 
     public static VoxelShape box(double minX, double minY, double minZ, double maxX, double maxY, double maxZ) {
@@ -47,30 +48,11 @@ public final class Shapes {
     }
 
     public static VoxelShape create(double minX, double minY, double minZ, double maxX, double maxY, double maxZ) {
-        if (!(maxX - minX < 1.0E-7D) && !(maxY - minY < 1.0E-7D) && !(maxZ - minZ < 1.0E-7D)) {
-            int i = findBits(minX, maxX);
-            int j = findBits(minY, maxY);
-            int k = findBits(minZ, maxZ);
-            if (i >= 0 && j >= 0 && k >= 0) {
-                if (i == 0 && j == 0 && k == 0) {
-                    return block();
-                } else {
-                    int l = 1 << i;
-                    int m = 1 << j;
-                    int n = 1 << k;
-                    BitSetDiscreteVoxelShape bitSetDiscreteVoxelShape = BitSetDiscreteVoxelShape.withFilledBounds(l, m, n, (int)Math.round(minX * (double)l), (int)Math.round(minY * (double)m), (int)Math.round(minZ * (double)n), (int)Math.round(maxX * (double)l), (int)Math.round(maxY * (double)m), (int)Math.round(maxZ * (double)n));
-                    return new CubeVoxelShape(bitSetDiscreteVoxelShape);
-                }
-            } else {
-                return new ArrayVoxelShape(BLOCK.shape, (DoubleList)DoubleArrayList.wrap(new double[]{minX, maxX}), (DoubleList)DoubleArrayList.wrap(new double[]{minY, maxY}), (DoubleList)DoubleArrayList.wrap(new double[]{minZ, maxZ}));
-            }
-        } else {
-            return empty();
-        }
+        return new io.papermc.paper.voxel.AABBVoxelShape(new AABB(minX, minY, minZ, maxX, maxY, maxZ)); // Paper
     }
 
     public static VoxelShape create(AABB box) {
-        return create(box.minX, box.minY, box.minZ, box.maxX, box.maxY, box.maxZ);
+        return new io.papermc.paper.voxel.AABBVoxelShape(box); // Paper
     }
 
     @VisibleForTesting
@@ -132,6 +114,20 @@ public final class Shapes {
     }
 
     public static boolean joinIsNotEmpty(VoxelShape shape1, VoxelShape shape2, BooleanOp predicate) {
+        // Paper start - optimise voxelshape
+        if (predicate == BooleanOp.AND) {
+            if (shape1 instanceof io.papermc.paper.voxel.AABBVoxelShape && shape2 instanceof io.papermc.paper.voxel.AABBVoxelShape) {
+                return io.papermc.paper.util.CollisionUtil.voxelShapeIntersect(((io.papermc.paper.voxel.AABBVoxelShape)shape1).aabb, ((io.papermc.paper.voxel.AABBVoxelShape)shape2).aabb);
+            } else if (shape1 instanceof io.papermc.paper.voxel.AABBVoxelShape && shape2 instanceof ArrayVoxelShape) {
+                return ((ArrayVoxelShape)shape2).intersects(((io.papermc.paper.voxel.AABBVoxelShape)shape1).aabb);
+            } else if (shape2 instanceof io.papermc.paper.voxel.AABBVoxelShape && shape1 instanceof ArrayVoxelShape) {
+                return ((ArrayVoxelShape)shape1).intersects(((io.papermc.paper.voxel.AABBVoxelShape)shape2).aabb);
+            }
+        }
+        return joinIsNotEmptyVanilla(shape1, shape2, predicate);
+    }
+    public static boolean joinIsNotEmptyVanilla(VoxelShape shape1, VoxelShape shape2, BooleanOp predicate) {
+        // Paper end - optimise voxelshape
         if (predicate.apply(false, false)) {
             throw (IllegalArgumentException)Util.pauseInIde(new IllegalArgumentException());
         } else {
@@ -285,6 +281,43 @@ public final class Shapes {
     }
 
     public static VoxelShape getFaceShape(VoxelShape shape, Direction direction) {
+        // Paper start - optimise shape creation here for lighting, as this shape is going to be used
+        // for transparency checks
+        if (shape == BLOCK || shape == BLOCK_OPTIMISED) {
+            return BLOCK_OPTIMISED;
+        } else if (shape == empty()) {
+            return empty();
+        }
+
+        if (shape instanceof io.papermc.paper.voxel.AABBVoxelShape) {
+            final AABB box = ((io.papermc.paper.voxel.AABBVoxelShape)shape).aabb;
+            switch (direction) {
+                case WEST: // -X
+                case EAST: { // +X
+                    final boolean useEmpty = direction == Direction.EAST ? !DoubleMath.fuzzyEquals(box.maxX, 1.0, io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON) :
+                            !DoubleMath.fuzzyEquals(box.minX, 0.0, io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON);
+                    return useEmpty ? empty() : new io.papermc.paper.voxel.AABBVoxelShape(new AABB(0.0, box.minY, box.minZ, 1.0, box.maxY, box.maxZ)).optimize();
+                }
+                case DOWN: // -Y
+                case UP: { // +Y
+                    final boolean useEmpty = direction == Direction.UP ? !DoubleMath.fuzzyEquals(box.maxY, 1.0, io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON) :
+                            !DoubleMath.fuzzyEquals(box.minY, 0.0, io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON);
+                    return useEmpty ? empty() : new io.papermc.paper.voxel.AABBVoxelShape(new AABB(box.minX, 0.0, box.minZ, box.maxX, 1.0, box.maxZ)).optimize();
+                }
+                case NORTH: // -Z
+                case SOUTH: { // +Z
+                    final boolean useEmpty = direction == Direction.SOUTH ? !DoubleMath.fuzzyEquals(box.maxZ, 1.0, io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON) :
+                            !DoubleMath.fuzzyEquals(box.minZ,0.0, io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON);
+                    return useEmpty ? empty() : new io.papermc.paper.voxel.AABBVoxelShape(new AABB(box.minX, box.minY, 0.0, box.maxX, box.maxY, 1.0)).optimize();
+                }
+            }
+        }
+
+        // fall back to vanilla
+        return getFaceShapeVanilla(shape, direction);
+    }
+    public static VoxelShape getFaceShapeVanilla(VoxelShape shape, Direction direction) {
+        // Paper end
         if (shape == block()) {
             return block();
         } else {
@@ -299,7 +332,7 @@ public final class Shapes {
                 i = 0;
             }
 
-            return (VoxelShape)(!bl ? empty() : new SliceShape(shape, axis, i));
+            return (VoxelShape)(!bl ? empty() : new SliceShape(shape, axis, i).optimize().optimize()); // Paper - first optimize converts to ArrayVoxelShape, second optimize could convert to AABBVoxelShape
         }
     }
 
@@ -324,6 +357,53 @@ public final class Shapes {
     }
 
     public static boolean faceShapeOccludes(VoxelShape one, VoxelShape two) {
+        // Paper start - try to optimise for the case where the shapes do _not_ occlude
+        // which is _most_ of the time in lighting
+        if (one == getFullUnoptimisedCube() || one == BLOCK_OPTIMISED
+                || two == getFullUnoptimisedCube() || two == BLOCK_OPTIMISED) {
+            return true;
+        }
+        boolean v1Empty = one == empty();
+        boolean v2Empty = two == empty();
+        if (v1Empty && v2Empty) {
+            return false;
+        }
+        if ((one instanceof io.papermc.paper.voxel.AABBVoxelShape || v1Empty)
+            && (two instanceof io.papermc.paper.voxel.AABBVoxelShape || v2Empty)) {
+            if (!v1Empty && !v2Empty && (one != two)) {
+                AABB boundingBox1 = ((io.papermc.paper.voxel.AABBVoxelShape)one).aabb;
+                AABB boundingBox2 = ((io.papermc.paper.voxel.AABBVoxelShape)two).aabb;
+                // can call it here in some cases
+
+                // check overall bounding box
+                double minY = Math.min(boundingBox1.minY, boundingBox2.minY);
+                double maxY = Math.max(boundingBox1.maxY, boundingBox2.maxY);
+                if (minY > io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON || maxY < (1 - io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON)) {
+                    return false;
+                }
+                double minX = Math.min(boundingBox1.minX, boundingBox2.minX);
+                double maxX = Math.max(boundingBox1.maxX, boundingBox2.maxX);
+                if (minX > io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON || maxX < (1 - io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON)) {
+                    return false;
+                }
+                double minZ = Math.min(boundingBox1.minZ, boundingBox2.minZ);
+                double maxZ = Math.max(boundingBox1.maxZ, boundingBox2.maxZ);
+                if (minZ > io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON || maxZ < (1 - io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON)) {
+                    return false;
+                }
+                // fall through to full merge check
+            } else {
+                AABB boundingBox = v1Empty ? ((io.papermc.paper.voxel.AABBVoxelShape)two).aabb : ((io.papermc.paper.voxel.AABBVoxelShape)one).aabb;
+                // check if the bounding box encloses the full cube
+                return (boundingBox.minY <= io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON && boundingBox.maxY >= (1 - io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON)) &&
+                       (boundingBox.minX <= io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON && boundingBox.maxX >= (1 - io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON)) &&
+                       (boundingBox.minZ <= io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON && boundingBox.maxZ >= (1 - io.papermc.paper.util.CollisionUtil.COLLISION_EPSILON));
+            }
+        }
+        return faceShapeOccludesVanilla(one, two);
+    }
+    public static boolean faceShapeOccludesVanilla(VoxelShape one, VoxelShape two) {
+        // Paper end
         if (one != block() && two != block()) {
             if (one.isEmpty() && two.isEmpty()) {
                 return false;
diff --git a/src/main/java/net/minecraft/world/phys/shapes/VoxelShape.java b/src/main/java/net/minecraft/world/phys/shapes/VoxelShape.java
index f325d76c79d63629200262a77eab7cdcc9beedfa..0ab742f38f79c150630bb9ba153d92d864aface1 100644
--- a/src/main/java/net/minecraft/world/phys/shapes/VoxelShape.java
+++ b/src/main/java/net/minecraft/world/phys/shapes/VoxelShape.java
@@ -16,11 +16,17 @@ import net.minecraft.world.phys.BlockHitResult;
 import net.minecraft.world.phys.Vec3;
 
 public abstract class VoxelShape {
-    protected final DiscreteVoxelShape shape;
+    public final DiscreteVoxelShape shape; // Paper - public
     @Nullable
     private VoxelShape[] faces;
 
-    VoxelShape(DiscreteVoxelShape voxels) {
+    // Paper start
+    public boolean intersects(AABB shape) {
+        return Shapes.joinIsNotEmpty(this, new io.papermc.paper.voxel.AABBVoxelShape(shape), BooleanOp.AND);
+    }
+    // Paper end
+
+    protected VoxelShape(DiscreteVoxelShape voxels) { // Paper - protected
         this.shape = voxels;
     }
 
@@ -163,7 +169,7 @@ public abstract class VoxelShape {
         }
     }
 
-    private VoxelShape calculateFace(Direction direction) {
+    protected VoxelShape calculateFace(Direction direction) { // Paper
         Direction.Axis axis = direction.getAxis();
         DoubleList doubleList = this.getCoords(axis);
         if (doubleList.size() == 2 && DoubleMath.fuzzyEquals(doubleList.getDouble(0), 0.0D, 1.0E-7D) && DoubleMath.fuzzyEquals(doubleList.getDouble(1), 1.0D, 1.0E-7D)) {