Comment 24 for bug 601986

Thanks for the reply and I'm glad it's not just me. I usually just figure I'm going crazy when things like pressing keys and moving the mouse seem to make a difference in speed. :]

I think the most direct clue is the effect of the nohz kernel option which I think controls the dynticks feature:

http://kernelnewbies.org/Linux_2_6_21#head-8547911895fda9cdff32a94771c8f5706d66bba0

So, since dynticks is on by default (aka, when we have this problem) that means that the scheduler is not necessarily being ticked. I am guessing that both your infinite loop program and the pressing of keys are compensating for a bug in dynticks related to this hardware (or a bug in the hardware I suppose) by forcing the scheduler to run. A key repeat rate of, say, 30Hz wouldn't be that far off the classic 100Hz continuous tick.