While experimenting with a previous problem in the 1.13.1 snapshot, I came across the fact that wherever I went, hostile mobs seemed to spawn everywhere and very rapidly, but disapearing after about a tick. Bats would also spawn frequently above ground but didnt disapear unlike the other mobs. All of this was found during the day while set to peaceful mode, and happened above ground level. This I believe caused my computer to freeze up every other second for several seconds, making it basically unplayable. I have not tested what happens when set to other difficulties, but neither the freezing, or the rapid mob spawning seemed to take place on the same map in 1.13. I hope this can get patched before release, I’m not sure how much more lag my computer can take before crashing. I can take screenshots or video if needed.