Board Thread:Bug Reports/@comment-173.127.23.188-20161121183547/@comment-27219153-20161121195008

Whenever you teleport to new chunks, it has to generate ~300 chunks instantly. Your CPU is not powerful enough to do this task in one tick (in fact I don't think any processor exists that can do this in one tick), thus it takes more than one tick, usually many more, and in your case, potentially upwards of 600 ticks. When the server gets behind like this, it stops processing network traffic, thus causing you to time out.

Since you said you didn't have problems with previous updates, maybe the mod has become slightly more CPU intensive? Like Mevans said, please provide the log, and also your server specs and amount of players at the time of the incident could prove useful as well.