10.6.7 Combo Update Slows MacBook Air 3D Performance

Several weeks ago I noticed a dramatic slowdown in the graphics performance of my late 2010 MAcBook Air, and after weeks of futile searching, and falsely diagnosing the problem as SSD degradation, I came across the article below on MacWorld:

http://www.macworld.com/article/158494/2011/04/1067updatemba.html

There, the authors described the same problem I was having, and attributed the dramatic graphics slowdown to a problem with drivers installed by the OS 10.6.7 update. I've done my own testing and found that the bad driver problem is specific to the 10.6.7 Combo Update.

I was able to completely restore graphics performance on my MAcBook Air to waht it should be (ie Portal 2 runs great) by following the steps described by commenter shawnyeager (Thanks Shawn!) in the MacWorld article, which I'm copying here for the benefit of others:

Boot off the MAcBook Air USB media, do an in-place install of 10.6.5 (it's non-destructive) and then download individual (non-combo) updaters for 10.6.6, 10.6.7 and 10.6.7 Supplemental. After applying them, Portal 2 is will run beautifully on a late 2010 MacBook Air with native resolution and 'Medium' to 'High' settings on all graphics options. The difference is dramatic.

Cheers!