i dont know what will be best for you, but i play .38mm pick (they are small as hell) and i can play just about ever fast lick in the book. so picks are mainly up to you. if you are having wrist controll on alternate picking, then maybe its the pick, but if its just speed, then you need to work on your picking speed.

just my opinion, dont go out and buy 8 differnt sets of picks and see which one suites you best.