Affects Version/s: Minecraft 18w43b, Minecraft 18w43c
Fix Version/s: None
Environment:Java 1.8.0 51 (64bit)
Windows 10 (64bit, latest updates)
16Go 3200MHz DDR4 RAM (4096MB allocated to Minecraft)
CPU: AMD Ryzen 7 2700X (8 cores, 16 threads @ ~4.0GHz (integrated auto overclocking))
GPU: GeForce GTX 1080, 2560x1387 windowed display resolution
GPU driver version: 416.34
When I change chunk (move from one chunk to another), there's always a freeze (edit: as said by Jay Eff in the comments, it starts a while after first loading the world for me too). See 2018-10-26_11-03-24.mp4 for illustration.
Happens since 18w43a.
Also, it doesn't happen on Minecraft 1.12.2 or 1.13.2.
Tested in 18w43c :
Launcher profile :
(Personnaly confirmed this bug in 18w43a and 18w43b (and not present in 1.12.2) with default unmodified profile = without custom java args)