Comment 9 for bug 347307

It's hard to know if the problem is Fluidsynth's fault. It could just as well be the alsa subsystem, or anything else eating CPU. But it could also be that Fluidsynth 1.0.8 eats more CPU than 1.0.7, causing underruns. If you like, you can try out 1.0.9 for Jaunty in my ppa, https://launchpad.net/~diwic/+archive/ppa , to see if that helps.

On the latency webpage, did you also read the section about bypassing pulseaudio/dmix (-o audio.alsa.device=plughw:0)? Or do you perhaps do not use pulseaudio or dmix at all?

About the bad timing, that has been fixed in Fluidsynth SVN and will work better in next release of Fluidsynth (which will be 1.1.0), so whether or not that will reach Karmic depends on when that next version is released.