i found a solution, dont use the SL viewer i tried phoenix firestorm, and nos SL is back to normal so its not a hardware/driver problem, just the original viewer
same here bought a new radeon hd 6950, upgraded from gf8800gts, clean reinstall win7 64, and SL is unplayable, soooo slow. latest drivers, ati catalyst 11.8, windows up to date. with gf8800 everything was super fast.