Hey Wolf,Optifine is a gamble try without it. Second try some JVM args like @Qazplm601's. Third try bumping up the available RAM to 2.5 or 3 gigs
Forgive my derpness, but for the Java Arguments, do I input them into the Advanced Options -->Additional Java Parameters? Sorry much of this Minecraft optimization is Greek to me.
Edit again: Got optifine taken care of.. *pulls body into corner*