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This is probably the answer you don't want to hear but don't use optifine. I've heard more than one mod developer (while listening to forgecraft streams) say that optifine is written poorly and should not be used with mods.
Optifine has a LOT of issues with mod compatibility with the more recent packs/mods (1.5.x and up)
For the least amount of issues, use the most recent (1.5.2 U D5).
Otherwise, don't use it.
Is there an performance enhancing alternative to optifine? my computers specs are kinda lacking, and with all the mods minecraft runs pretty slow without optifine.