So when I use Photoshop, it lags so much. When I move the cursor down the tool bar, the tools box's glow after already being passed. When I move the actual Photoshop window, it moves and stops and then moves and stops. When I draw with the paint tool it does the same thing: moves and stops, moves and stops.
If it helps at all, when I opened the performance window to change stuff, I noticed that the problems were gone. Don't know what that means, but it is really weird. I open the performance window, and the tools glow when they should and (while i can't actually do anything) it seems to work.
Try turning off (unticking) Use Graphics Processor in Photoshop Preferences under the Performance tab.
Please check the graphic card driver, update it if necessary, check the quantity of free RAM and the free space on the system HD...