How to Resolve High CPU Usage by Antimalware Service Executable (MsMpEng)

The Antimalware Service Executable process, also known as MsMpEng.exe, is part of Windows Defender, Microsoft’s built-in antivirus software. While it plays a crucial role in protecting your computer from malware, it can sometimes cause high CPU usage, leading to system slowdowns. In this guide, we’ll explore why MsMpEng might be using so much CPU and how to fix the issue to ensure your system runs smoothly.

Understanding Antimalware Service Executable (MsMpEng.exe)

What Is MsMpEng.exe?

MsMpEng.exe is the core process of Windows Defender. It handles real-time protection by scanning files for potential threats as you access them, running background scans, and performing other security-related tasks. While these activities are essential for keeping your system secure, they can sometimes consume a significant amount of CPU resources.

Why Does MsMpEng.exe Cause High CPU Usage?

High CPU usage by MsMpEng.exe can occur for several reasons, including:

• Full system scans running during active use
• Conflicts with other software
• Large files or archives being scanned
• Outdated Windows Defender definitions

How to Fix High CPU Usage by MsMpEng.exe

If you’re experiencing high CPU usage due to Antimalware Service Executable, here are several methods you can try to resolve the issue.

1. Change Windows Defender’s Scheduled Scan Time

One of the most common causes of high CPU usage is Windows Defender running a full system scan during active hours. You can change the scan schedule to a time when you’re not using your computer.

Steps:

1. Open Task Scheduler:
   • Press Win + S, type Task Scheduler, and press Enter.
2. Navigate to Windows Defender Tasks:
   • In Task Scheduler, go to Task Scheduler Library > Microsoft > Windows > Windows Defender.
3. Adjust Scan Schedule:
   • Double-click on Windows Defender Scheduled Scan.
   • Go to the Triggers tab, select an existing trigger, and click Edit.
   • Set the scan to run at a time when your computer is idle.
4. Save and Exit:
   • Click OK to save your changes and exit Task Scheduler.

2. Limit CPU Usage for MsMpEng.exe

You can limit the amount of CPU power that MsMpEng.exe is allowed to use during scans by modifying Windows Defender’s settings.

Steps:

1. Open Command Prompt as Administrator:
   • Press Win + X and select Command Prompt (Admin).
2. Limit CPU Usage:
   • Type the following command and press Enter:
     shell

     %ProgramFiles%\Windows Defender\MpCmdRun.exe -limitaccess -scantimeout 50

3. Restart Your Computer:
   • Restart your computer to apply the changes.

3. Add MsMpEng.exe to the Exclusion List

Another effective way to reduce CPU usage is to exclude MsMpEng.exe from being scanned by Windows Defender itself. This prevents the antivirus from scanning its own process.

Steps:

1. Open Windows Security:
   • Press Win + I to open Settings.
   • Go to Update & Security > Windows Security > Virus & threat protection.
2. Manage Settings:
   • Scroll down and click on Manage settings under Virus & threat protection settings.
3. Add an Exclusion:
   • Scroll down to Exclusions and click Add or remove exclusions.
   • Click Add an exclusion, select Process, and type MsMpEng.exe.
4. Save and Exit:
   • Click Add to confirm the exclusion.

4. Disable Windows Defender in Favor of Third-Party Antivirus (If Necessary)

If Windows Defender continues to cause performance issues, and you’re comfortable with using a different antivirus solution, you can disable Windows Defender and install a third-party antivirus.

Steps:

1. Open Settings:
   • Press Win + I to open Settings.
2. Navigate to Windows Security:
   • Go to Update & Security > Windows Security.
3. Turn Off Real-Time Protection:
   • Click on Virus & threat protection, then Manage settings.
   • Turn off Real-time protection.
4. Install Third-Party Antivirus:
   • Choose and install a reliable third-party antivirus software.
5. Disable Windows Defender Permanently (Optional):
   • If you decide to disable Windows Defender permanently, use Group Policy or Registry Editor to do so.

5. Update Windows and Windows Defender

Outdated Windows Defender definitions or an outdated Windows version can cause issues. Ensure that both are up to date to prevent unnecessary CPU usage.

Steps:

1. Check for Windows Updates:
   • Press Win + I to open Settings.
   • Go to Update & Security > Windows Update.
   • Click Check for updates and install any available updates.
2. Update Windows Defender Definitions:
   • In the Virus & threat protection settings, click Check for updates under Virus & threat protection updates.
3. Restart Your Computer:
   • After installing updates, restart your computer and check if CPU usage has decreased.

Conclusion

High CPU usage by Antimalware Service Executable (MsMpEng.exe) can significantly impact your computer’s performance. By following the steps outlined in this guide—such as adjusting the scan schedule, limiting CPU usage, adding exclusions, or considering a third-party antivirus—you can effectively reduce the resource consumption of MsMpEng.exe. Keeping your system and antivirus definitions up to date is also crucial in ensuring optimal performance.