Comment 81 for bug 190754

I haven't had time to play around with this yet, but from this developer blog http://0pointer.de/blog/projects/pulse-glitch-free.html ,

"PulseAudio <= 0.9.10 uses a fragment size of 25ms by default, with four fragments. That means that right now, unless you reconfigure your PulseAudio manually clients will not get latencies lower than 100ms whatever you try, and as long as music is playing you will get 40 interrupts/s. (The relevant configuration options for PulseAudio are default-fragments= and default-fragment-size-msec= in daemon.conf)

dmix uses 16 fragments by default with a size of 21 ms each (on my system at least -- this varies, depending on your hardware). You can't get less than 47 interrupts/s. (You can change the parameters in .asoundrc)".

It appears that pulse-glitch-free is going to be merged into the main trunk as 0.9.11 , so that may solve the problem.