There is a recently released patch on the live servers which fixes quite a few performance issues within the game. "Black fuzzies" in Arachnos missions have been stomped out for those that are running GeForce 8800 series cards as have the drum sounds for the drum emotes for better performance. Aside from those issues, there are fixes to costume pieces and selling related problems. You can read the full patch notes right here!
http://www.cityofheroes.com/news/patch_notes.html