I recently installed the new creative suite on my pc and photoshop cs2 is running very slow compared to my version of cs. It's pretty buggy, I'll be selecting different layers or tools and it lags and then catches up to my last click maybe 2 to 3 seconds later.

I checked my scratch disk and memory settings, the scratch disk is set to a 2nd internal hard drive and my memory usage is set to the default of 50%. I have 1gb of pc3200 memory. What's an optimal percentage to keep it at in order to improve performance, but not slow down my other apps considerably.

http://photoshopnews.com/2005/07/07/memory-allocation-and-usage-photoshop-cs2-2/