When you scan your Windows 11/10 using Windows Defender or Windows Security, by default, a maximum of 50% of the CPU is utilized. However, if you’re seeing a more of your CPU utilization, you can limit it using selective settings.
In this article, we’ll show you the methods to limit maximum CPU utilization during a Windows Defender scan. If you’re an IT admin, you can easily use these methods in your organization and deploy same settings to different client machines.
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Limit CPU usage during Defender scan in Windows 11
Method 1: Using Windows PowerShell
1. Right click Start Button or press 
+ X keys and select Windows PowerShell (Admin).
2. In administrative Windows PowerShell window, paste following and press Enter key:
Get-MpPreference | select ScanAvgCPULoadFactor
3. Previous command will show the default set value ScanAvgCPULoadFactor, which is actually the load on CPU during a scan. It’s default value is 50%. To set it to your desired value, type following command by substituting XX with value between 05 to 100 and press Enter.
Set-MpPreference -ScanAvgCPULoadFactor XX
For example, to set CPU utilization to 30% during a Windows Defender scan, I’d execute Set-MpPreference -ScanAvgCPULoadFactor 30 command.
4. Once command executed successfully, your setting are in effect. Close Windows PowerShell.
Method 2: Using Group Policy
1. Press Windows + R and put gpedit.msc in Run dialog box to open GPO snap-in. Click OK.
2. Next, in the GPO snap-in window, navigate here:
Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus > Scan
3. In the right pane of Scan folder, find out the policy setting named Specify the maximum percentage of CPU utilization during a scan. Double click on it to modify its status:
4. Set the policy status to Enabled. Under Options, set the percentage value for CPU utilization during a scan. This value can be between 5 to 100. Click Apply, OK then.
5. Close Group Policy and refresh GP engine by either rebooting or running gpupdate /force command. Your configured settings should be in effect now.
That’s it!
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Aha! There is a policy to limit Defender CPU usage.
Well- that tells you all you need to know. It tells you that the software was developed without any thought to how it could grind a machine to a halt, and that to help manage the crappy implementation after-the-fact they added some esoteric configuration to enable you to limit CPU usage. And then, of course, they didn’t do the obvious follow-on which would be to set a DEFAULT VALUE which would cap the thing by default. Also missing- they could have set processor or thread affinity so that it didn’t take ALL the PC resources.
So here I am, with many other people, poking around the web trying to figure out how to get Defender to not consume the processor. And here we are- seeing that the way to do it is some after-the-fact hack that they threw together because of how they wrote the thing to begin with.
I have enough of a background in systems and software that I have no doubt this is how it ended up this way. Anyone who knows any different… Feel free to chime in.
Hi,
This isn’t a hard limit. Even with setting that it will still go over the limit at times.