Thanks for that detail !
This program seems to multi-thread very well according to SL's CPU Usage monitor.
I think the 10.6 changes "in the deep" will exspecially use much Cores better than 10.5 - even without special
source coding changes. But recompiling source with newest Xcode & using 10.6 dev framework needed , i think.
Also, even if the app itself is really small (< 100 KB) is uses much RAM (up to 60 MB!) and also interacts much with it.
So also the Systembus Speed and RAM Speed may be computed (in the CPU time!).
So DDR3 tripple channel vs DDR3 dual channel (2 Modules same size) vs DDR2 vs RAM Latency timings vs RAM MHz ... will give different CPU time usage. GPU time should not be so much affcted by that (RAM/Systembus speed)