The culprit was a missing, incompatible change in alsa-lib's snd_pcm_hw_params_choose() that PulseAudio relies on. Because Karmic does not ship the changesets required, you're seeing pretty horrible performance. I've uploaded a staging version of alsa-lib with these fixes to the ubuntu-audio-dev PPA. Please test and verify that it resolves the issue for you.
The culprit was a missing, incompatible change in alsa-lib's snd_pcm_ hw_params_ choose( ) that PulseAudio relies on. Because Karmic does not ship the changesets required, you're seeing pretty horrible performance. I've uploaded a staging version of alsa-lib with these fixes to the ubuntu-audio-dev PPA. Please test and verify that it resolves the issue for you.