ATI Catalyst 6.5 vs 6.4 Performance Comparison
 

The Catalyst 6.5 runs with us so far stably and error free. The improvements/Hotfix are enumerated. As well as the driver gets our recommendation it there is very fast, and that is probably again the most important, the newest Hotfix/improvements contained. This time there is a “Chuck” Patch to see simultaneous again around Oblivion in HDR and AA.

Apart from the performance improvements you can see below, Adaptive Anti-Aliasing has been added to the Radeon 9550 and above models. Originally Adaptive AA, which is a feature which adjusts its detail level depending on the performance, was only seen in the X1000 series of cards.
http://www.tweaktown.com/articles/904/