This is a trick which will enable you to control the prioritization of processes or Tasks. The CPU tasks are performed in an orderly way. This registry hack is used to change the way tasks are performed. It is not possible to explain this tweak without getting into many technical details. In short what it does is, it forces short processor time-slices to be allocated to foreground processes three times more often than the time-slices given to background processes. This will give more priority to foreground tasks than background tasks. To do this..
Navigate to:
HLM\SYSTEM\CurrentControlSet\Control\PriorityControl
Set the DWORD Win32PrioritySeparation to, well, any of a number of values.
3 (the default): Foreground and background tasks have equal priority.
2: Foreground tasks have higher priority than background tasks
1: Foreground tasks have maximum priority
0 (not recommended): Foreground tasks run in real-time.
This will most likely make your system hang, and is primarily to be used in mission-critical environments with supporting hardware.
Note: This particular tweak should not be applied to a system running either SQL Server or IIS unless you’re certain that you want to slow down those background processes.