Windows 11 comes with Microsoft Defender Antivirus built in. It scans your computer to keep it safe from viruses and malware. But here’s the problem: these scans can use a lot of your computer’s power (CPU). When that happens, other things you’re doing slow down.
The good news? You can control how much CPU Microsoft Defender uses. This guide shows you easy ways to change those settings. Your computer will run smoother.
What is Microsoft Defender Antivirus?
Microsoft Defender Antivirus is built into Windows 11. It regularly scans your computer to keep it safe from harmful software.
By default, Defender uses about 50% of your CPU during scans. On slower computers, this might make things feel sluggish. You can lower this number to use less CPU. But keep in mind: lowering it too much might make scans take longer.
Why Would You Want to Change This?
Lowering CPU usage helps your PC run smoother while Defender scans. You can still work on other things without everything getting slow.
How to Change CPU Usage During Scans
You can adjust the CPU usage for scans using one of these simple methods:
1. Using PowerShell (Easy for Everyone)
PowerShell is a tool in Windows that lets you type commands to change settings.
Step 1: Open PowerShell as Administrator Click here to learn how to open PowerShell. Or: Press Windows key + S, type PowerShell, right-click it, and select Run as administrator. [ADMIN REQUIRED]
Step 2: Check your current CPU limit
Copy and paste this command and press Enter:
Get-MpPreference | select ScanAvgCPULoadFactorYou will see a number showing the current CPU limit (usually 50).
Step 3: Set a new CPU limit
Use this command. Replace <percentage> with a number between 0 and 100:
Set-MpPreference -ScanAvgCPULoadFactor <percentage>Example: To limit Defender to use only 30% CPU, run:
Set-MpPreference -ScanAvgCPULoadFactor 30Step 4: Restart your computer
Restart to apply the new setting.
2. Using Local Group Policy Editor (For Windows 11 Pro or Enterprise)
This tool lets you change settings in Windows with a simple interface.
Step 1: Open Local Group Policy Editor
Press Windows key + R, type gpedit.msc, and press Enter. [ADMIN REQUIRED]
Step 2: Navigate to the Scan folder
Go to this location:
Computer Configuration → Administrative Templates → Windows Components → Microsoft Defender Antivirus → Scan
Step 3: Find and edit the CPU setting
Select the Scan folder on the left. Then double-click “Specify the maximum percentage of CPU utilization during a scan” on the right.
Step 4: Enable and set your percentage
Choose Enabled. Then enter the CPU percentage you want (0 to 100).
Step 5: Apply changes
Click Apply and OK.
Step 6: Restart your computer
Restart to make the changes take effect.
3. Using Windows Registry Editor (If Group Policy Editor is not available)
Be careful with this one! The Registry stores important Windows settings.
Step 1: Open Registry Editor
Press Windows key + R, type regedit, and press Enter. [ADMIN REQUIRED]
Step 2: Navigate to the Defender Scan folder
Go to this location:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\ScanStep 3: Create the Scan folder if it doesn’t exist
If you don’t see the Scan folder, right-click on Windows Defender. Choose New → Key, and name it Scan.
Step 4: Create a new value
Click on the Scan folder. On the right side, right-click and choose New → DWORD (32-bit) Value. Name it AvgCPULoadFactor.
Step 5: Set the CPU percentage
Double-click AvgCPULoadFactor. Set the Base to Decimal. Enter a number between 0 and 100 for CPU usage. (Default is 50)
Step 6: Save and close
Click OK and close the Registry Editor.
Step 7: Restart your computer
Restart to apply changes.
Important Note: Always back up your registry before making changes. Mistakes can cause problems with Windows.
What Happens When You Lower CPU Usage?
Your computer will feel faster during Defender scans. Other programs and tasks will run smoother. The trade-off: Defender scans might take longer to complete.
Summary
Microsoft Defender Antivirus scans your PC to keep it safe. But these scans can use a lot of CPU. This makes your computer feel slow.
You can change how much CPU it uses. Use PowerShell, Local Group Policy Editor, or Registry Editor. Choose the method that works best for you.
Lowering CPU usage helps your PC run smoother during scans. But scans might take a bit longer.
Always restart your PC after changing settings. This makes sure the changes work.
For more official information, see Configure scanning options for Microsoft Defender.
If you have questions or tips, feel free to share them in the comments below!
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