I wanted to try the new Catalyst 10.8 drivers for my 5850, moving up from the 10.7 drivers, and they caused a large hit in frame rate.
Without changing any other settings, the frame rate dropped between 10 and 15 FPS.
I searched a bit and found that other users experienced the same thing, so I reverted back to the 10.7 drivers and everything was back to the way it was.
So, I wanted to post this to give a heads up to anybody else thinking of installing the Catalyst 10.8 drivers.
mir