Profiling the 1.12.2 crafting issue with Sampler atm, but it also generated these stall reports that may be of use to you:

stall-2018-02-03_23.10.25-1.txt
stall-2018-02-03_23.11.25-2.txt
stall-2018-02-03_23.09.55.txt

This is probably due to Modern Skyblock 2 having a crapload of OreDict entries, but, who knows!

Need sampler files..

stall-2018-02-04_21.38.54.txt

This is the best I can give you because I can't do a Sample as the game is loading. I might be able to capture a profile from Netbeans by hand.

Sorry, I really need a profiler report.

There's no way to use Sampler to generate a report at startup, but it's easy to reproduce with recipes that have a lot of different paths/oredict entries.