Deathsneeze

This change also breaks mob switches. in prior versions we could load entities in non-entity processing chunks and save a bit of lag. 

This change also will result in more portals being needed to keep an area loaded that does not necessarily need to be entity processing, say for example larger main storage systems or furnace arrays, 

I fail to understand what this change was even trying to fix, all it does is break things that worked just fine in previous versions

Can also confirm, happens even localhost server hosted on same machine as client instance. Is absolutely not a network related issue

I can also confirm this issue as well, compared to earlier snapshots leading up to the pre-releases the performance was similar to 1.15, however in 1.16.1 when running a tree farm that I would get 20fps before, I now get around a 1 frame per minute framerate. 

The issue seems to be due to client side light updates, after some testing. Reducing light so that both block light and skylight are 0 so that lighting updates are not processed at all seems to help tremendously, although the client side performance is still quite poor compared to older versions of the game.