I seem to recollect encountering a related issue once, back around the 'Big Daddy' day, when I was wondering why video playback on a K6-2/500 machine seemed regularly 'skippy'. The answer to that particular problem turned out to be a simple editing of /etc/gamin.rc, in order to disable its polling. I was wondering if a similar condition may be affecting my system today; however, a quick lsof doesn't seem to indicate gamin-anything... so, I'm supposing now that it's likely something else instead. I had wondered about the XFS filesystem a bit, but then here's rudge on the other hand, stating that his ext3-based system suffers the same behaviour. Hal? Possibly. Again, I really don't know, so that's why I'm enquiring.
Edit: rudge, from the listing you posted above it does indeed seem to be a behaviour that could be attributable to the hal daemon. Is there any way to reconfigure same, such that it would avoid any polling of certain designated devices?