So what is msmpeng.exe and how can you prevent it from slowing your system down? Well, unlike what you may have read elsewhere, it is not spyware or malware. It’s actually quite ironic because it’s associated with Windows Defender, the anti-spyware product from Microsoft.
Unfortunately, this crappy piece of software is already installed on Windows Vista and it also comes with Windows Live One Care. There are two ways to stop msmpeng.exe from using system resources: exclude the Windows Defender directory from scanning or simply turn off Windows Defender.
Exclude directory for scanning
If you would like to keep using Windows Defender, then your only chance of fixing the high processor usage issue is to prevent the Windows Defender directory from being scanned.Apparently, the service scans it’s self and therefore eats up all the CPU. Open Windows Defender, click on Tools and then Options. Now scroll down to the Advanced Options section:
Now click on the add button under the “Do not scan these files or locations” section. Now type in the path for the Windows Defender directory:
c:\program files\windows defenderClick OK and now make sure to click the Save button. Hopefully this will fix your high CPU usage error with Windows Defender. Also be sure to read my post on how to customize all the options for Windows Defender like what stuff to monitor in real-time, etc.
Turn off Windows Defender
The other option is to simply turn off Windows Defender, which I think is a better idea anyway. There are lots of other spyware programs out there that are much better than Windows Defender.To turn off Windows Defender, open the program and click on Options. Now go to Administrator options and uncheck the Use Windows Defender box. Make sure to click Save.