I used options from your xorg and I did tests with different InitialPixmapPlacement values. It's strange, but there wasn't almost any difference in performance +/- 3secs (there was some improvement with 169.12 and I'll do tests with this driver too). I did only gtkperf -a -c 100.
Then please tell me what distribution,
what version of X11 you are using,
whether this is x86 or x86_64,
what driver version etc
I'm using Kubuntu 8.04 right now, but I used earlier versions before, Ubuntu and Xubuntu 7.10, Fedora 8 and Archlinux and performance was comparable. I'll install Archlinux and do some more testing.
X.Org X Server 126.96.36.199, nvidia driver 173.08.
When I typed: nvidia-settings --glxinfo there was an error:
ERROR: Error fetching GLX Information: Unknown Error
Maybe there are some library conflicts. When drawing box by a cursor on desktop, xorg cpu usage is almost 100%. Direct rendering is enabled and 3D acceleration works. I'm not using laptop so I suppose that powermizer doesn't affect performance.
Thanks for your patience.