Our 1.7.10 Cauldron server has been having some crafting related problems stemming from Extra Trees. We've been noticing major TPS drops (sometimes as low as 7) from crafting, and after a good bit of profiling we've slightly figured the cause.
The method "binnie.extratrees.block.decor.NBTShapedRecipe.func_77569_a()" will spike to anywhere from 20% to 80% of server CPU time when someone's crafting a slightly large amount of items (anywhere from like a stack or more). We think it's something to do with your mod checking if the crafted item belongs to it.
It may well be an incompatibility somewhere, so I'm not going to just blame ExtraTrees.
However, if ET is indeed the cause, is this something that could be fixed soon?
Shame EB and ET are closed source, (cough) or we'd just do a pull request to save you some time (cough cough), but that's unfortunately.. yeah.
I'll provide any further info needed.