Windows Defender on Windows 7 eats up all the CPU time?


  • Hi, we recently set up a new 32-bit Windows 7 professional machine. On it we have Kaspersky anti-virus, Perforce server, and MySQL/bugzilla/Apache. Nothing else, the machine is fully up to date, and on a Windows domain (designated as a server). Running on decent new HP server hardware, under VMWare ESX.

    But the CPU usage on it was always very high and the machine utterly sluggish and unresponsive (took a minute literally to open the task manager). The task manager showed the p4 service consuming up to 40% of the CPU and svchost consuming about 60% or more of the CPU time, and this went on continuously (for over a week while I was monitoring it), even if I restarted. This really aggravated me. So using the sys internals tool process explorer, I managed to identify that this svchost process that was eating up all the CPU time was running "secsvcs". Googling this told me it was associated with Windows Defender. Since we also have Kaspersky on the machine, I opened Windows Defender and turned it off. Now with that change, the machine instantly became super responsive again, purring like a puppy and the CPU usage now remains near zero (the perforce server now also uses little CPU, it was likely using more earlier because it was starved).

    So I dont know what Windows Defender was doing that was eating up so much CPU for so long. We have several other Windows 7 machines as well, and have only seen this same issue manifest on one other machine. But Googling suggests that other people out there have run into this exact issue as well.

    Any ideas or suggestions are welcome. Or alternatively, consider this a performance optimization for your Windows 7 machine.
    Wednesday, December 22, 2010 3:29 PM


All replies

  • Hi,

    please make a xperf trace [1] to diagnostic the high CPU usage. Please upload the etl file to your SkyDrive [2] and post a link here.

    I'll take a look at it, maybe I can see more details.


    "A programmer is just a tool which converts caffeine into code" CLIP- Stellvertreter
    Wednesday, December 22, 2010 3:56 PM
  • If you have another antivirus, you don't need Defender.  Microsoft Security Essentials disables Defender as well.


    Wednesday, December 22, 2010 4:19 PM
  • I just experienced that Windows Defender used a lot of CPU and crashed on Vista, and repeated this over and over, thus keeping the CPU at 100%.

    I launched Process Monitor, and the problem was that I had a 6 GByte zip file on the Desktop, and the Windows Defender scanned the poor zip-file and then failed, and then started over.

    I deleted the zip file, and now my Windows Defender was able to complete its scan without crashing, and thrashing my harddisk.

    Not sure why background priority for I/O and all that other nice stuff that was added with Windows Vista doesn't keep the Windows Defender from thrashing the system.

    Thursday, March 29, 2012 2:38 PM