What do you mean by "even Cider ports0"? Cider ports are the ones which perform the worst anyway.
Try World Of Warcraft. Has slightly better performance on OS X than it does on Windows. (Yes I tested on the same machine with Windows 7 x64 vs Snow Leopard).
But yes in general gaming on OS X sucks. Developers need to really put in effort and money like Blizzard to make their games run decently on OS X.
This is opposite of what I found on my previous iMac 3.06 w/8800gs. With Windows 7 -- I forget the exact increase -- WoW did perform better than it did using SL. I've also heard other people around here stating a performance boost when playing games such as WoW under Boot Camp.