Reminder: If you use Windows you *have* to read these posts

Just spent hours defragging, reg cleaning (multiple tools) and compacting, and seriously, the most dramatic performance gain was after disabling one 3rd party context menu extension.

http://n074h4x0r.blogspot.com/2005/12/obscure-windows-gem-of-week-context.html
http://n074h4x0r.blogspot.com/2005/12/offending-extensions-pgp-81.html