I recently upgraded to Catalyst 11.6 and found there was a marked decrease in performance compared to 11.5. After experimentation, I found that SSAO was the culprit. There's a massive drop in FPS on my machine after upgrading to 11.6. More so than the hit SSAO imposed before.
Plays really good with the new beta patch and no SSAO. Additionally, removing the mirror gave me another 8 FPS or so
Thought I'd share that in case it helps anyone.
AMD HD5870
i7 920 @3-8Ghz