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Windows Update High CPU

Love them or hate them, Windows Updates are an essential part of securing your computer.  Windows Update Shield and high CPUUnfortunately, they’re not without their problems. 

Windows releases it’s monthly Windows Updates on the second Tuesday of every month (known as Patch Tuesday).  Over the last couple of months, we’ve noticed certain PC’s (generally Windows XP) on our network being crippled by high CPU usage, on the Wednesday immediately after Patch Tuesday.  They tend to correct themselves over the course of a day or two – but that’s not really acceptable on a production network!

Having performed virus and malware scans (both negative), it was time to broaden the investigation.  We suspected it was to do with Windows Updates (as this had happened at the same time last month), but looking at Task Manager didn’t give too much away initially.  We could see one of the svchost.exe processes was hogging all the CPU.  As there are usually multiple svchost.exe processes running, it’s worth enabling the PID column (in Task Manager / View / Show Columns / tick PID checkbox).  Now, going to a command prompt and typing tasklist /SVC lists all the running processes.  Comparing against our busy svchost.exe process in Task Manager, we could see that the wuauserv service (Windows Update) was one of the services running within the busy svchost.exe process.

After scouring the net, I found loads of other people had started to experience the same issue over the last couple of months.  Some cited a conspiracy theory that Microsoft was introducing these problems into Windows XP to force users to consider upgrading their OS (I shall keep my opinions to myself!), with support for XP running out next year.  Others came up with the (not so) great solution of disabling Windows Updates altogether.  Some suggested Office updates were the issue – but in our case, the PC’s affected were not running Office, but were pretty basic installs.

No one individual solution seemed to work for me, but a combination of them did.  We found that the affected PC’s generally ran Windows XP SP3, with IE7 installed.

The Solution

So, here’s what we did (disclaimer: this worked for us, but I can’t guarantee it’ll work for everyone!)…

  1. Login as an administrator
  2. Install Internet Explorer 8 – choose without updates during the install (Download Microsoft IE 8)
  3. Install Microsoft Hotfix KB2870699 for your OS and for IE8 (Download Microsoft Hotfix KB2870699)
  4. Clear out the files in the Windows Software Distribution folder, from a command prompt:
    • net stop “Automatic Updates”
    • del /f /s /q %windir%\SoftwareDistribution\*.*
    • net start “Automatic Updates”
  5. Reboot, and login as the end user. 
  6. Optionally force Windows Updates to kick in:
    • From a command prompt, type: wuauclt.exe /detectnow
  7. Monitor the CPU usage, and yes, there may be a CPU spike for a few minutes as it gathers the updates – but that is normal behavior, as long as it calms down after a few minutes.

 

Conclusion

The solution is pretty simple, but a little painful (running the IE 8 install takes a while) – although I’d suggest doing it before the next Patch Tuesday, or expect the phones to be hot for a day or two!

I hope this helps, and good luck!!

 

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