Since the upgrade to Karmic on my desktop, graphic performance has gone down considerably. I solved this in the past by downgrading Nvidia, but since Lucid, this has become impossible. It's not that I cannot live without the desktop bling, but suspend-resume is impossible without running the Nvidia drivers. The problem manifest itself by very high CPU bursts by kernel processes (kondemand, ksoftirqd), which makes the desktop unworkably slow.
I tried everything, from disabling PAT, KMS modesetting, switching framebuffers, all without success. I even tried to enable Lenny's Nvidia drivers, but that pulled in a 2.6.26 kernel, which I cannot use, because my filesystems are ext4.
I eventually turned in despair to the Nvidia website, looking for older drivers. The 173 release was still available in the archive download section, which came as a ncurses-based installer. These Nvidia based drivers are famous for messing up a Linux system, so I was rather reluctant to use those. I still decided to give them a go, which rather went surprisingly really well.
Finally a performant system again !