Windows Defender is Microsoft default and a most solid line of defence when it comes to a consumer’s cyber-protection. However, those of you running Windows 10 on older PCs may notice that Windows Defender ‘s max CPU usage for scans can be quite high at times.

If that is the case, then knowing how to reduce the CPU usage may help you in the long run.

Use PowerShell to change Windows Defender’s max CPU usage

This is an easy procedure, but care must be taken as you are using PowerShell with administrator rights

1. Open PowerShell with administrative rights
2. Type in or copy-paste the following command:
   • Get-MpPreference | select ScanAvgCPULoadFactor
   • By doing this, you will display the current CPU usage percentage limit for Windows Defender.
3. To change the value, type in or copy-paste the following command:
   • Set-MpPreference -ScanAvgCPULoadFactor <percentage>

Keep note that the value of <percentage> needs to be between 5 and 100.

If you set the percentage value to 0, it will remove the CPU limit and allow Windows Defender to use up even 100% of it. This is not recommended as it can lead to unresponsive apps, freezing and even overheating.

Change Windows Defender max CPU usage using registries

1. Press Win + R
2. Type in regedit.exe
   • This will open the Registry Editor
3. Go to the following Registry key:
   • HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindows DefenderScan
4. Edit or make a new 32-bit DWORD value AvgCPULoadFactor
5. Switch the value data editor to Decimal
6. Set the value data to a value of 5 to 100

If you want to undo the change, simply delete the DWORD you created.

Change Windows Defender max CPU usage using Group Policy

1. Press Win + R
2. Type in gpedit.msc
   • The Group Policy Editor will open
3. Go to Computer Configuration
4. Go to Administrative Templates/Windows Components/Microsoft Defender Antivirus/Scan
5. Double-click on the Specify the maximum percentage of CPU utilization during a scan policy
6. Enable it
7. Enter the desired CPU limit under Specify the maximum percentage of CPU utilization during a scan
8. Select Apply
9. Click OK

A final note

By following these steps, you can manage the average CPU usage that your Windows Defender uses up during scans.

For more information contact Ryan Danvers of ABACON IT on 072 601 2858