My computer started up pretty fast when I first got it in 2007 - Tiger operating system. It got slower. When I upgraded to Snow leopard, I thought it would help. I think user data that was transferred makes it slow. I start the computer and wait 45 seconds for the desktop to load, then I click mail, Safari and Firefox. Takes about a minute to open. It used to be faster. Isn't there something I can clean out or do to speed this up. Is there something I should be doing for maintenance with my Mac to keep it running fast in general? Thanks for any tips.