The world just hangs, then when you save and exit it freezes but doesn't crash. I have to crash the mod from task manager which produces no crash report

I'll be needing much more than just this.

Clearly, you have a lot of other stuff going on there. So we'll have to see what's what and try to pinpoint what is actually happening.

We have fixed a very common server hang in a recent version. Please try updating. If that doesn't fix it, reopen the ticket.