How to Change Windows Defender Max CPU Usage on Windows 11: Step-by-Step Guide

Windows Defender is the built-in antivirus program in Windows 11, designed to protect your computer from malware and other threats. Sometimes, during a scan, it can use a high amount of your CPU, causing your computer to slow down. Adjusting the maximum CPU usage for Windows Defender can help balance protection and system performance.

This guide will walk you through the basic steps to change the CPU usage limit for Windows Defender on Windows 11. Each step is explained in simple terms, so even beginners can follow along easily. By the end, you will know how to optimize Windows Defender to work smoothly without overloading your system.

Keep in mind that changing these settings allows you to control how much of your computer’s power Defender uses during scans. This is especially helpful if you want to keep your PC responsive while running security checks.

Let’s get started with the step-by-step instructions.

Quick Note Before You Begin

Ensure you are logged into Windows 11 with an administrator account, as changing Defender settings requires admin privileges.
Make sure Windows Defender is active and up to date. You can check this in the Windows Security app.
Backing up your system or creating a restore point is recommended before changing system settings.
This guide focuses on limiting CPU usage during full system scans, not real-time protection.

Step 1: Open Windows Security

Click on the Start button (Windows icon) usually found at the bottom-left corner of your screen. Then, type Windows Security in the search bar and press Enter. This opens the main security hub for your PC where you can access Defender settings.

Step 2: Access Virus & Threat Protection Settings

Once Windows Security is open, find and click on the Virus & threat protection section. This area contains all the options related to antivirus scanning and threat management.

Next, scroll down and click on Manage settings under the Virus & threat protection settings heading. This opens detailed options for how Defender operates.

Step 3: Open the PowerShell or Command Prompt as Administrator

To adjust CPU usage limits, you will need to use a special command. For this, open PowerShell or Command Prompt with administrator rights:

Click the Start button again.
Type PowerShell or cmd in the search bar.
Right-click on the result and select Run as administrator.
If prompted by a security warning, click Yes to allow.

Running commands as an administrator is important because changing system-level settings requires higher permission.

Step 4: Check the Current CPU Usage Limit

In the PowerShell or Command Prompt window, type the following command and press Enter:

Get-MpPreference | Select-Object -Property ScanAvgCPULoadFactor

This command shows the current CPU usage limit set for Windows Defender scans. The value is a percentage of your CPU that Defender will use during scanning (default is often 50%).

Step 5: Set a New Maximum CPU Usage Limit

To change the CPU usage limit, enter the following command, replacing XX with the number representing the percentage of CPU you want Defender to use (for example, 30 for 30%):

Set-MpPreference -ScanAvgCPULoadFactor XX

For example, to limit CPU usage to 30%, type:

Set-MpPreference -ScanAvgCPULoadFactor 30

Press Enter to apply the change. This setting helps reduce the CPU load while Defender runs scans, making your computer more responsive.

Step 6: Verify the Change

To confirm that the new limit has been applied, run the check command from Step 4 again:

Get-MpPreference | Select-Object -Property ScanAvgCPULoadFactor

The output should reflect the new CPU usage percentage you set.

Alternative Method: Using Group Policy Editor (For Windows 11 Pro and Above)

If you prefer a graphical interface and your Windows edition supports it, you can change the CPU limit via the Group Policy Editor:

Press Win + R to open the Run dialog box.
Type gpedit.msc and press Enter.
Navigate to Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus > Scan.
Find and double-click on the Specify the maximum percentage of CPU utilization during a scan setting.
Select Enabled, then enter the desired CPU usage percentage.
Click Apply and OK.

This method is easier for some users but is not available on Windows 11 Home edition.

FAQs

Can I set CPU usage to 100% to make scans faster?

While technically possible, setting CPU usage to 100% may cause your computer to slow down or become unresponsive during scans. It’s best to find a balance that suits your needs.

Does changing CPU usage affect real-time protection?

No. These settings only affect scheduled or manual full scans, not real-time protection, which runs continuously in the background.

What if I don’t see a change in CPU usage after adjusting the setting?

Ensure you have administrative privileges and that the command was entered correctly. Also, changes take effect during full scans, so try running a manual full scan to see the difference.

Can I revert to default settings?

Yes. To reset the CPU usage limit to default, run the following command in PowerShell as administrator:

Set-MpPreference -ScanAvgCPULoadFactor 50

When Nothing Works

If you are unable to change the CPU usage limit or Windows Defender is not behaving as expected, consider these options:

Restart your computer and try the steps again.
Check for Windows updates and install any pending updates, as they may fix bugs.
Use the Windows Troubleshooter by searching for “Troubleshoot settings” in the Start menu and running the tool for Windows Security.
Visit the official Microsoft Support page for Windows Security for further assistance.

Conclusion

Managing Windows Defender’s CPU usage on Windows 11 is a simple yet effective way to maintain your PC’s performance while keeping it protected. By following this step-by-step guide, you can easily adjust how much processing power Defender uses during scans.

Remember to always run these commands with administrator rights and check your settings after making changes. Whether you prefer using PowerShell or the Group Policy Editor, both methods give you control over Defender’s impact on your system.

With these tips, you can enjoy a smoother computing experience without compromising your security.