Yesterday I investigated a Windows XP machine that had become so slow it was unusable. It was a Dell Dimension 2350 with 1GB RAM and a 2.00 Ghz Celeron CPU – not too bad a spec for XP – that had been out of use for a while and was being brought back into service for a specific and undemanding task. At first it had performed fine, but after applying Service Pack 3 and installing Microsoft Security Essentials it had ground almost to a halt. The machine performed so badly that trying to troubleshoot it was like wading through glue. You could get task manager up and see plenty of RAM free, but the CPU was stuck on 100%.

After trying a few futile things like updating the BIOS, I installed Process Explorer and Process Monitor from Sysinternals. Looking at the activity summary in Proccess Monitor it was obvious which process was to blame: an instance of svchost.exe started with the command line: c:\windows\system32\svchost.exe –k netsvcs

However, netsvcs is responsible for many different services. I did a bit more poking around with Process Explorer and found the culprit: Windows Automatic Updates. Typing:

net stop wuauserv

at a command prompt fixed the problem temporarily.

It appears that the Windows Update database, which you can find in %windir%\Software Distribution\DataStore, can get corrupted. The Windows Update service goes into a spin and consumes all your computing resources. You can turn Automatic Updates off by right-clicking My Computer, Properties, and Automatic Updates tab; or you can fix it the brute-force way by deleting the DataStore folder and letting Windows recreate it, though you lose your update history; or you can try to repair the database.

Of course there are many reasons why Windows XP might run slowly, and often it is not easy to troubleshoot. There is abundant well-meaning advice on the internet, much of it based on the assumption that malware is involved, but finding the right answer to a particular problem is a matter of luck. In a professional context, it is hardly worth the time and corporates will just re-image the machine.

I do find it interesting that when Windows XP first appeared in 2001 it specified a minimum of 64MB RAM and ran OK in 128MB. Once fully patched with Service Pack 3, automatic updates, Internet Explorer 8 and anti-virus, it needs at least 512MB and in my experience 1GB to be comfortable. Unfortunately you have little choice; if you want to connect to the Internet or run recent applications, you have to update it. Automatic updates is a also a near-essential security feature.

Finally, kudos to the Sysinternals team whose tools are invaluable for solving this kind of problem.