Finally. I think I've just managed to significantly improve the IV performance. Not only that only parsing is now faster, 10 mass melters in one row no longer kill your FPS 
BTW, that wonderful method is caching. The new method will be worse memory-wise, but will be TONS better performance-wise.
EDIT:
New method is 26 times better the old one 
I'll upload the new version, lemme know if it's better with a lot of mods than the older one.
EDIT 2:
On vanilla + 15 mods:
2013-11-15 18:48:21 [INFO] [LevelStorage] Clearing IV cache, 148 ItemStack, 27 OreDict
2013-11-15 18:48:22 [INFO] [LevelStorage] Clearing IV cache, 298 ItemStack, 47 OreDict
2013-11-15 18:48:22 [INFO] [LevelStorage] Clearing IV cache, 1 ItemStack, 0 OreDict
2013-11-15 18:48:22 [INFO] [LevelStorage] Total recipes iterated: 2301
2013-11-15 18:48:22 [INFO] [LevelStorage] Total time consumed: 2830
2013-11-15 18:48:22 [INFO] [LevelStorage] Average ms per recipe: 1
2013-11-15 18:48:22 [INFO] [LevelStorage] IVRecipeParser took 3090ms.
EDIT 3:
New version is up. Merely bugfixes and some performance enhancements.
EDIT 4:
And oh, once again I forgot to change DEBUG variable to false... Sorry for the spam in the console.