Adobe's Guide to Tuning Photoshop for Peak Performance
If you do a lot of Photoshop work, it behooves you to spend some time to configure the application (and the computer it's running on) to achieve peak performance. The time you spend optimizing your Photoshop environment will almost certainly pay back big efficiency dividends. But how do you know how to optimize Photoshop's performance? There are many factors at work, and it takes an expert approach to really fine tune all the options to squeeze every last drop of speed out of your machine. Fortunately, the Photoshop team has posted a new, extensive guide on How to Tune Photoshop for Peak Performance.
For hardware topics, guide includes sections on RAM, hard disk storage, processors, graphics cards, and monitors. For Photoshop itself, the guide has a set of key steps to follow including allocating scratch disk space, optimizing cache settings, choosing the right file format, optimizing images, and much, much more.
And by the way, if you haven't upgraded to CS6, the CS5 version of the guide is still available.