Comment 22 for bug 107545

Could it be that your test-app runs with a nice value above zero? You can check this with command "top" (column "NI"). If so, then you can make you cpu accelerate by executing the two commands:
$ sudo su
$ echo 0 >/sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice_load

I've no experience with kernel 2.6.30 yet. But a sampling_rate of 80000 should be low enough. My startup-script sets it to 60000 and everything runs jitter-free (including flash videos and wine Starcraft ;-).