Game crashed after creating new caves of chaos world

Put the summary of the bug you're having here

What I expected to happen was...:
I expected to be able to play on a Caves of Chaos preset survival world

What actually happened was...:
World generated with some effort, game crashed after playing for a few minutes

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...generate caves of chaos world
3. ...set vision to 16 chunks
4....start playing, maybe for 5 minutes max