Please allow me to shed some light on the subject.
(Copy and Paste)
This one's for experts. The length of time which Windows executes one thread before it can switch to another thread is referred to as a quantum. These intervals can be fixed or variable, long or short, and can be biased towards foreground or background threads.
By editing the process quanta control settings you can get much more precise control over how your system schedules threading. For instance, if you've got a server that runs primarily background processes, you'll want to set the system to favour those and use long fixed-length timeslices to let everything run in as much a parallel fashion as possible.
The key that holds this information, HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\PriorityControl, has a value named Win32PrioritySeparation. This value is a bitmask, so setting it can be a little tricky. Start with the value 0 and add the following values to it.
If you want to set the ratio of foreground-to-background threads to:
3:1, add 2.
2:1, add 1.
1:1, add 0.
If you want to set the lengths of the quanta to:
Variable lengths: add 4.
Fixed lengths: add 8.
Variable-length quantas are useful if you have some processes that kick in and use a lot of CPU intermittently, but don't run non-stop. This way the OS can adjust the amount of time devoted so that timeslices are more evenly distributed between processes.
If you want to set the intervals for quanta to be:
Shorter: add 32.
Longer: add 16.
eg. 38 =
Short, Variable Length with 3:1 allocation.
I use 20 so I have Long, Variable Length with 1:1 allocation.
Hope this helps.