How to limit or set Maximum CPU Usage for Windows Defender Scan

Windows Defender Antivirus has a maximum 50% CPU usage for a scan by default in Windows 10. But, you can specify a percentage of CPU usage you want Windows Defender Antivirus to not exceed. In this post, we will show you how to check current maximum CPU Usage for Scan and a quick way to specify maximum CPU Usage for Scan by Windows Defender.

Windows Defender runs mostly in the background. It scans new files for threats, and will also examine any file that you download via Edge, Chrome, or some other browser. A full system scan won’t run while you’re actively using your PC. However, if you want to limit Windows Defender CPU usage so that it never uses the CPU too much, you can.

How to check current maximum CPU Usage for Windows Defender scan

Launch PowerShell in elevated mode.

Copy and paste the command below into the elevated PowerShell, and hit Enter.

Get-MpPreference | select ScanAvgCPULoadFactor

From the result, you’ll see the ScanAvgCPULoadFactor value for the current maximum percentage CPU usage for a scan.

Now you have been able to see your PC’s current maximum percentage CPU usage for a scan by Windows Defender; you can now set a higher or lower percentage CPU usage as the case may be.

Specify maximum CPU Usage for Windows Defender scans

You can increase, reduce, limit, or set a CPU usage limit for Windows Defender scans in Windows 10 by using any one of the following methods. The default is 50%.

1. Using PowerShell command
2. Using Group Policy Editor
3. Using Windows Registry.

You will need administrative privileges to perform this action.

1] Using PowerShell command

Launch PowerShell in elevated mode.

Type the command below into the elevated PowerShell, and hit Enter.

Set-MpPreference -ScanAvgCPULoadFactor <percentage>

Substitute the place-holder <percentage> in the command with a value between 5 to 100. Example:

Set-MpPreference -ScanAvgCPULoadFactor 30

Specifying a value of 0 (zero) will disable CPU throttling for Windows Defender, allowing Windows Defender to use as much CPU as it wants.

NOTE: If the Windows Defender antivirus service is disabled on your machine you may receive an Operation failed error.

2] Using Group Policy Editor

Open Group Policy Editor and navigate to the following setting:

Computer Configuration/Administrative Templates/Windows Components/Windows Defender Antivirus/Scan

On the right pane, double-click on Specify the maximum percentage of CPU utilization during a scan setting.

Select Enabled and set a figure.

Click Apply and restart your computer.

NOTE: On some systems /Windows Defender Antivirus/ appears as /Microsoft Defender Antivirus/.

3] Using Windows Registry

Open Registry Editor and navigate to the following key:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender

Right-click on Windows Defender key > Select New > Key and name it as Scan.

Next, right-click on this newly-created Scan subkey, select New > DWORD (32-bit) Value. Name it as AvgCPULoadFactor and give it a value between 5-100 to specify the maximum CPU percentage for Windows Defender scans.

This is how you can limit Windows Defender scan’s CPU usage.