This is Tom, Jeans' lazy husband.
Steven, what I did in OS X is run the periodic repair routines. These are: empty caches, update prebindings and repair permissions. These are Unix maintenance routines that OS X runs automatically if your computer is on at 3am. That's all I know - I have no idea why these routines are required, what they do, or why they run automatically at 3am!
What I do know is that every so often - regardless of whether the computer has been on all night or not - I run these routines from a freeware program called "Cocktail", which also performs a number of other maintenance tasks. You can download "Cocktail" from
http://www.dicom.se (it's a German site).
There are other useful maintenance programs that can be found at VersionTracker (
http://www.versiontracker.com/index.shtml) under 'utilities'.