The MixinIdentifier injector can cause high amounts of CallbackInfoReturnable allocations in conjunction with mods that create an Identifier on every tick. While it could be argued mods should be caching those, that's not something that's very easy to solve in the short term. I would recommend switching to ModifyReturnValue from MixinExtras to alleviate the problem as well as to improve the compatibility of the injection overall.

I identified this through profiling, don't have a specific screenshot on hand but I can provide one if absolutely necessary.