Alright, I try from the start without Optifine.
Oh, another thing while we're here... Is it normal for IC2 to cause immense lag? When I had it on 1.8.1 I had the same lag as normal, but for some reason (and I can confirm that it's IC2, because it was the same when I tried with just IC2 and not the other mods) IC2 for 1.0 causes serious lag. It's not unplayable, but it certainly limits the enjoyment.
Edit: Not using Optifine fixed it. Thanks for the help guys <3