Affects Version/s: Minecraft 18w50a
Fix Version/s: None
Operating system: Windows 7
Java version: Version 8 Update 181 (Build 1.8.0_181-b13)
CPU: Intel Core i5-6200U @ 2.30GHz 2.30GHz
4 GB RAM
Intel HD Graphics 520
Flat world, with fast clouds and almost no buildings.
Heavy lags when a redstone clock is turned on. It is a 16-tick clock, so not very fast.
Reloading chunks doesn't work. Low graphic settings don't work either.
I didn't have this problem in Version 1.13.x.