Strange world generation lag and a fix for it.

The bug!

I have a low-end pc and a want to play my favourite game. So I created a new bug report that similar to MC-123779(similar but it can be the solution to fix that bug and it is not a duplicate) and I discovered a strange thing. I tested on a superflat world. The world was laggy if I selected the "classic flat" world present. After I tried the "overworld" present and the world was smooth and optimised.

In the "classic flat" world present:

➖ Game running with: 50-130 ms

➖ Framerate: 10-30 fps

In the "overworld" world present:

➕ Game running with: 7-24 ms

➕ Framerate: 45-60 fps

Solution:

I am not a dev and I can't help you with code but I think if some developer look after about this I guess the devs can finally fix the default world chunk loading lag bug(I think this bug about chunk loading but I don't know). I hope helped something about this because many people waiting for optifine mod to optimise the vanilla game.