[1.] One line summary of the problem: Dragging a window in X makes the system "hang" until button is released.
[2.] Full description of the problem/report:
"Hang" means xmms's sound output stops, and if I'm running something
like "while :; do echo hi; sleep 1; done" in a different window, that
also stops writing "hi" until I release the mouse button. (Then I
get a whole bunch of them all at once.) This seems to rule out ALSA
being the cause, which was originally my first thought.
I've tried with and without CONFIG_PREEMPT enabled. I've tried changing
X to be un-niced. I've tried applying the patch-test4-O20int patch from
Con Kolivas. That last patch seems to have increased the time it takes
for the problem to kick in (it's on the order of 5 seconds now instead
of 3 seconds), but it didn't fix it.