Comment 6 for bug 326149

Jaunty has a startup script called /etc/init.d/ondemand which sleeps for 60 seconds to allow login and then tries to set the governor to ondemand (that explains why sometimes my Jaunty boots up in performance mode, not ondemand mode). You could try adding the 'echo 30 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/up_threshold' in there. I noticed that if you set one up_threshold, the other CPU's up_threshold also changes so you probably don't need to do CPU1 as well.

Bug #107545 is the opposite of this bug! It seems that Ubuntu used to use a much lower value of 31 but then changed it to 95 (why? I read the default is supposed to be 80).

It still doesn't explain why I get good performance after rebooting but it then degrades with time. Perhaps the ondemand governor's sampling rate drops with time.