I seem to be having the same problem you're in whenever I
exit firefox I get a slow reaction from my mouse from my
computer experience I think it's due to accidently removing certain registries on accident you might wanna try to see if you got a emergency cd thats refreshes the whole os or just the registry although there is an alternative way to fix the registry by going to start then run type in command after that type in scanreg /fix it should fix the registry though it hasn't worked for me but might for you