One way I've found to cure a sluggish Mac is to limit the amount of fonts loaded in OS X. By default OS X loads a number of fonts that aren't required by the operating system. On top of that, Microsoft Office and Adobe's Suite of applications add several fonts that aren't required.
![extensis font management](https://www.streamcreative.com/hs-fs/hub/86417/file-15793310-jpg/images/extensis_font_management.jpg)