Helping people with computers... one answer at a time.
Occasionally one program will use up all of your computers processing resources. Using process explorer it's easy to figure out which program that is.
My machine is slower than molasses in the winter time, and I suspect that one or more programs are simply using up all available CPU time. How do I tell which ones they might be so that I can turn them off, or whatever?
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Yep, that sounds slow.
Actually it happens to me from time to time as well. A program will decide it has something very very important to do, and decides to use your computer and all of its processing power to do it.
The good news is it's easy to find out which program that might be.
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All evidence to the contrary, computers can really only do one thing at a time. OK, a dual core or dual processor machine can do exactly two things at a time, a quad core can do 4, and so on. But a single CPU can do exactly only one thing at a time. It just switches between them all really, really quickly.
So when one program needs all of the CPU's attention, other programs that need the CPU might not get enough time to do their work. That typically results in a very slow system, from a user's perspective.
We can use task manager to figure out who the culprit is, but I very much prefer the free download Process Explorer. Download and run it, and you should see something very much like this:
The default display shows all he tasks running on your computer, in hierarchical order, meaning that if program A was the one that started program B, then program B appears indented beneath program A. That can be helpful for other reasons, but not what we want here.
Click on the column labeled CPU, and Process Explorer will sort the processes by CPU usage. The processes using the most CPU will be listed at the top:
Here you can see that when I took this image my CPU was actually 68% idle; in other words the it was doing nothing at all two thirds of the time. The next highest program on the list was SnagIt, the screen capture program I use, using about 14% of CPU, followed by Windows Explorer, Trillian, and others in decreasing order.
Here's another example after starting up an audio processing utility:
Here that program is using about 50% of my CPU's available processing power.
In many reports I get it's a program called "svchost.exe" that has people concerned and mystified. I've talked about svchost, and why there might be more than one copy running on your machine before. As of this writing there's a common problem that people are experiencing involving the Windows Update service causing its instance of svchost to use all available CPU. If right click on the svchost that appears at the top of Process Explorer's CPU usage list, click on Properties, and then click on the Services tab, you'll see all the system services that instance of svchost is providing:
You'll see that this is the instance of svchost that handles Automatic Updates on my machine, and that I have the option of stopping that service right there.
Regardless of what's actually causing your CPU usage problems, if you're having any, Process Explorer is a quick way to not only identify the culprit, but as its name implies, Explore some of the interesting information about the processes running on your machine.
Article C3003 - April 24, 2007
Leo A. Notenboom has been playing with computers since he
was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed.
After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers
to common computer and technical questions. More about Leo.
Time after time over the past 10 years of using WinXP (now SP3) I've found that it's always the "DNS Client" service that's taking up all my (single) CPU's cycles after a Windows Update. Simply disabling that service whenever I see _svchost_ going berserk immediately brings my computer back to its normal operating state, and there are absolutely no negative consequences in terms of web-surfing. Try it and see if it works for you.
Posted by: Frank D at April 20, 2010 9:29 AMThis is great. It should help me determine why my wife's computer is so slow, before I do a clean reinstall of everything.
Posted by: Steve Bukosky at April 20, 2010 9:55 AMFew things any of us do really uses much of the CPU (burning DVDs, movie editing, etc are some examples that do)... most of the time when you have a performance problem it is from another source than pure CPU usage. Four primary culprits are: disk access contention; memory saturation; network saturation; lock contention. My home systems are almost always at 100% CPU usage with no problems as we use background processes doing real science: see http://www.worldcommunitygrid.org/ for more information.
Posted by: Nicholas Gimbrone at April 21, 2010 5:27 PMOK, I've found the cause, but how do I tell if this is something that can be removed, deleted, disabled, etc.? I don't know enough to know what might disable or even crash my machine.
Posted by: Bombay Granny at April 22, 2010 5:49 AMUsing either Task Manager or Process Explorer, with nothing open except one IE page (yours), System Idle Process ranges for the CPU column as 75-95. Your comments indicate this is a percentage. Under the Performance tab, the graphics for CPU Usage and CPU Usage History are ranging 0-40-50%. And, at the bottom of Task Manager the number of prcesses open is indicated along with Commit Charge and CPU Usage in a range of 5-18%. What are the difference between the two CPU usage percentages then? I still have not been able to figure out why some execute files such as iexplore.exe, explore.exe, taskmgr.exe also keep bouncing around with different CPU and Mem Usage numbers. Thank you.
Posted by: David Cox at January 16, 2012 11:26 AM