When changing the priority of a process Windows 7 warns:

Changing the priority of certain processes could cause system instability.

System instability warning

Should I care? what does it even mean? what are the implications of "system instability"?


No, it's just a warning. You probably aren't going to cause any problems by turning the priority of a process up or down a notch. And there won't be any irreversible damage; anything you do mess up can be fixed by a restart. Just make sure to save your work first before experimenting!

There are a couple of common things that can go wrong (and thus that you should watch out for):

  • You can crank up the priority of a non-system process so high that it can cause the system to become unstable and non-responsive because the system processes don't get enough time.

  • You can crank down the priority of a system process so low that it doesn't get enough time, causing your system to become unstable and non-responsive. (Although I think they've fixed some of this more recently by preventing you from altering the priority of certain so-called "critical" system processes.)

In my experience, assuming a decently fast and stable machine, as long as you stay away from the "Real Time" option, you will be fine. Turning non-system process down in priority level is even less likely to cause harm.

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  • Why should I stay away from "Real Time"? is it just too high? (TBH I kinda want to use it) – MasterMastic Mar 29 '13 at 22:21
  • Yes it is, in most cases but you can give it a shot just make sure the process settings is set to manual start - that way you can reboot and recover if it becomes unstable – TomEus Mar 30 '13 at 3:18
  • Been there done that, high no problem, and if the process is not going to lockup the whole system anyways it isn't "needed" to be any higher. if the process is a type that can take all of the cpu(s) things come crashing down (even). Lockups that you cant get out of. A person can always set the "other" processes to idle. Some people would say there is never a need to adjust,and windows will handle it, but by tweaking both items, the one you want to background (idle), and the one you want to use(high), you can get most of the way there. Play a game even while the cpu is loaded with tasks. – Psycogeek Mar 30 '13 at 12:36
  • @Psycogeek What I want to set higher is the compiler's processes (cl.exe csc.exe etc.). Speeding up compiling that would take a very long time would just be so sweet! BTW, how can I set a process to idle? – MasterMastic Apr 1 '13 at 9:48
  • @ken Oops, idle is called LOW in windows 7 task manager. If you just have One single process that you are trying to get to go faster, adjusting it up to high will do at most ~0.5% and is never worth messing with. It will knock a few system tasks back some, and that is nothing. This prioritising only becomes useful when you want one working task taking a lot of cpu, to prioritize over another working task. – Psycogeek Apr 1 '13 at 9:59

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