This article will help you to diagnose common problems such as lack of maintenance, permissions conflicts and Hard Drive glitches that cause your Mac to run slowly.
There are two main routes to take to make your Mac as lean and mean as it was when you bought it (or even more so!)—hardware upgrades and software maintenance. One of the easiest things to do is to purchase additional RAM. As a rule, I say you can never have too much RAM. If you don't have at least 2GB of RAM, you should immediately upgrade. In addition to RAM, you should consider getting a faster hard drive (an SSD drive is what I recommend–more on that later). If your Mac is more than five years old, however, you might want to consider purchasing a new one, especially if you're running newer applications or the latest version of Mac OS X.
The following are essential utilities for keeping your Mac running smoothly and for fixing little problems that may crop up (Click the links to go to their download sites):