Found this out a while ago, its quite good after using some memory eating software or something else that seems to make your computer go slow after running it.

Goto Start -> Run -> type "Rundll32.exe advapi32.dll,ProcessIdleTasks"

It will run for a bit then your computer should run alot faster.

I also made a batch file for it.

just goto notepad and create a file and call it something.bat

Enter the following text into it and save.

@echo off
echo All Idle Processes Are Currently Being Processed.
echo Please Wait....
Rundll32.exe advapi32.dll,ProcessIdleTasks
cls
echo All Idle Processes Have Been Processed.
pause