While the option remains a powerful tool we recommend everyone use, 30s is
proving to be a bit much for certain gametypes and many admins are confused
that after updating they are now facing extreme loaded chunk counts.
We do recommend experienced users configure this value as needed, but we
cannot keep it as a default option given the variety of gametypes, the
potential inexperience of new users, and previous users upgrading and
now facing extreme chunk counts that offer little benefit.
When players are moving in the world, doing things such as building or exploring,
they will commonly go back and forth in a small area. This causes a ton of chunk load
and unload activity on the edge chunks of their view distance.
A simple back and forth movement in 6 blocks could spam a chunk to thrash a
loading and unload cycle over and over again.
This is very wasteful. This system introduces a delay of inactivity on a chunk
before it actually unloads, which is maintained separately from ChunkGC.
This allows servers with smaller worlds who do less long distance exploring to stop
wasting cpu cycles on saving/unloading/reloading chunks repeatedly.