Performance problem on AMD64-based system

[Guest Kal]

Okay... so here's an interesting, baffling technical quirk I've run into.

 

The two computers involved;

IBM Thinkpad R40 (Type 2681) (Roughly 2 years old iirc)

Pentium 4 M 1.8Ghz

256MB

ATI Mobility w/16MB

(OS X compatible network/audio work fine)

 

AMD64 3200+ (Winchester core)

1GB

Geforce FX5900XT 128MB

(Again, compatible network and audio - though audio is pitched up)

 

The story so far;

Okay, both PC and laptop are running IDENTICAL installs of OS X. Same exact images used, same exact commands used, same 0.5 patches, same resolution, colour depth etc. As near as damned identical as I can make them. Both are running SSE2, the laptop uses VESA 2.0 and the PC uses VESA 3.0. In every possible way the AMD machine should kick the laptop to pieces in terms of performance, right? Much faster processor, stacks more memory and a far superior video card etc.

 

A simple test shows me otherwise. Namely, the standard "Flurry" screensaver. Running on the laptop, it will work full-screen at 100% speed that it should. No dropped frames etc. It is perfect.

On the AMD64 PC it is a completely different story. The same screensaver runs absurdly slow. Jerky, dropped frames, whatever you want to call it; It runs like {censored} no matter what tweaks I try.

Using XBench, the ONLY thing the laptop outperforms on is the opengl/quartz tests. Quartz Extreme etc are most definitely not enabled on either machine, and no kexts appear to be loaded for either machine's graphics either.

 

Can anyone reason why on earth this could happen?