High CPU Usage by MsMpEng.exe

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Norbetow920

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May 5, 2019
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Hi,
There are many causes where my computer will freeze as AntiMalware Service Executable takes up 60-80% of my CPU. When I open Windows Defender and turn off real-time protection, the problem is resolved, but I would prefer to continue it. I've never had a problem with this before.

Have you had this issue or found a solution? Please let me know.

Thanks!
 

djbaxter

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What version of Windows are you using? Do you know what hardware your system is running and how much RAM is installed?

This is an article from 2017. My experience is that more recent versions of both Windows 10 and Windows Defender have been vastly improved since then but the article does give a number of suggestions for minimizing the issue you're experiencing.


For most people, the high memory usage caused by Antimalware Service Executable typically happens when Windows Defender is running a full scan. We can remedy this by scheduling the scans to take place at a time when you’re less likely to feel the drain on your CPU.

windows-task-scheduler.png

Optimize the full scan schedule.
  1. Open the Start menu, type “task scheduler” and click the top result to launch the program.
  2. In the navigation pane on the left, double click Task Scheduler Library. Continue to expand these folders and navigate to the following destination: Library/Microsoft/Windows/Windows Defender.
  3. When you have opened the Windows Defender folder, double click Windows Defender Scheduled Scan, located in the middle pane.
  4. Click the Conditions tab, uncheck all options and click OK. This will clear your scheduled scans.
  5. To protect your computer, it is important to schedule some new scans, but we can do this in a way that will reduce the impact on your system’s performance. To do so, double click Windows Defender Scheduled Scan, select the Triggers tab and click New.
  6. Create a new scan schedule that suits your needs, selecting options that strike the balance between protection and system efficiency. As a guideline, we recommend (at minimum) weekly scans at a time when you’ll be unlikely to notice the increased CPU usage.
  7. Repeat the process for the three remaining services (Windows Defender Cache Maintenance, Windows Defender Cleanup, Windows Defender Verification) found in the Library/Microsoft/Windows/Windows Defender folder.
Fix #2: Add Antimalware Service Executable to Windows Defender’s exclusion list

During its scans, Windows Defender checks every single file on your computer – including itself. This can occasionally result in some interesting interactions and is a common source of system lag. To prevent this from happening, you can simply instruct Windows Defender to skip itself when performing a system scan.

windows-defender-exclusions.png

  1. Press Ctrl + Shift + Esc to open Windows Task Manager.
  2. In the list of processes, search for Antimalware Service Executable. Right click on the process and select Open File Location.
  3. In the address bar, you’ll see the full path of Antimalware Service Executable. Click on the address bar and copy the full path.
  4. Open the Start menu, type “windows defender” and click the top result to launch the Windows Defender Security Center.
  5. Click on Virus & threat protection, then on Virus & threat protection settings.
  6. Scroll down until “Exclusions” and click Add or remove exclusions. In the next screen, click on Add an exclusion, select Folder and paste the path to Antimalware Service Executable (MsMpEng.exe) in the address bar. Finally click Open and the folder will now be excluded from the scan.
 

djbaxter

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Using windows 10 pro and installed 4 gb ram
That's a big part of the problem there.

I know that Microsoft claims that Windows will run on as little as 2 GB RAM but that's not realistic in the real world. I would strongly recommend upgrading that to at least 8 GB and if you can to 16 GB. You will notice a huge improvement. And last time I checked RAM is still relatively cheap. Just be sure to match the exact type of RAM for your computer.

In the meantime, see my post above regarding changing the schedule so that Windows Defender runs during the middle of the night when you're asleep.
 

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