Re: glxgears stutters in Fedora, not in Ubuntu
I had experienced the exact same issue as the OP... passing "nopat" to the kernel has resolved this problem!
Although I haven't used glxgears, disregarding the OP's direct comparison is asinine. I have used a variety of applications (X-Plane is one) that performed better under Ubuntu 8.X than in Fedora 9/10. Nopat is clearly the reason... adding nopat as a kernel argument has fixed the jitter and poor framerate I previously experienced.
Thank you for those who recommended this fix!