According to the Apple Support documentation, Mac OS X Update 10.5.6 "includes general improvements to gaming performance." We ran a series of tests to see what improved.
IXNAY on AMESGAY
We're not bothering to post any 3D Game benchmark graphs because of the five demanding examples we tested, only one ran faster under 10.5.6: Call of Duty 4. Even then, it only ran faster on the MacBook Pro 2.8 with the GeForce 9600M GT (15% gain). The Mac Pro 3.2 with both GeForce 8800 GT and Radeon HD 3870 posted times essentially identical to the previous OS rev.
MOTION SICKNESS CURED
What is worthy of note is a "fix" that enables Motion 3 to render RAM previews faster for certain templates. In our comparison of OS X 10.5.4 with 10.5.5, we discovered that the "Blocks - Detail" HD template took twice as long to render after the update than before the update.
We posted our findings after confirming them. At the time we didn't have a way to share this information directly with Apple or nVidia engineering. But they did notice our posting and we are pleased to report that with 10.5.6, the render speed is back to "normal."
The APPLE MOTION test we use measures in seconds the time to complete a "RAM Preview - Play Range" which renders the template on the fly using both CPU and GPU while storing the resulting rendered sequence in RAM -- if you have enough. We feature "Blocks Detail" HD template (900 frames) here because it was the 'problem child' for the GeForce 8800 GT the 10.5.5 OS X update.
Notice the Radeon HD 3870 "Mac and PC Edition" renders the preview faster than the GeForce 8800 GT in all three versions of Mac OS X.
STONE DESIGN IMAGINATOR
This app was created to showcase Core Image effects. We use it to test the GPU's ability to process those effects by having it render 1000 frames on the fly as it morphs from a snow leopard to a rose. (Graph displays time in seconds for the second cycle.)
Assuming this test is truly predictive of Core Image performance, the newest update of OS X does Core Image processing more slowly.