Minecraft Version: 1.10.2
Inventory Tweaks Version: 1.61-58
crash-2016-11-21_18.40.27-client.txt

Doesn't happen the first few times upon loading a fresh world, but once it starts happening, it doesn't go away.

This looks maybe related to #394 ?

I think I found the culprit in Crafting Harmonics - it's a MineTweaker style mod whose main feature is allowing recipe changes during gameplay. I was using it pretty heavily and I suspect it was causing a lot of lag when loading a world.