Macs get slower with prolonged use, much like Windows machines. Mac OS X, however, is really just UNIX, so Macs don’t have registries. Hence they are pretty easy to clean up. This tutorial will show you how to make things right on your Mac gone slow, and without spending a dime. Or even a minute of phone time.
You will need the following:
1) Admin access to your machine
Get that stuff, then proceed.
First, close every open application1. You can do this by hitting Command-Tab, selecting a running app, hitting Command-Q, and repeating until the only application left is Finder (you can’t quit that). Next, open a Finder window and navigate to Applications/Utilities. Launch Disk Utility.
Click the Repair Disk Permissions button. The process could take 15 to 20 minutes, so be patient. When it’s done, quit Disk Utility (again Command-Q).