Under Windows 7 I frequently get serious keyboard lag. My home machine (Windows XP) NEVER lags. I was able to improve things somewhat by running Mathematica as Administrator, but this only went so far. The machine is very powerful, has tons of memory.
The symptom is that any keypress or mouse click takes a second or two before anything happens. It is EXTREMELY annoying. You click the left arrow key, wait, click arrow key again, wait, click arrow key again, wait,... eventually you get to the place you need to be. If you hold the arrow key down, the system hangs then 5 seconds later the cursor appears 4 words over.
Other applications running on the same computer at the same time show no effect. Word, Excel, even total memory hogs like Adobe Illustrator run and respond immediately to keystrokes. Only Mathematica is displaying this lag.
I guess I can use a assembly language debugger to find out where the loop is that is lagging it out, but I am hoping somebody can save me the agony of doing this.