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Resolving High Hard Disk Drive and CPU Usage During Scans by Windows Defender

Summary: The following article deals with resolving an issue with the laptop or desktop locking up. This is because of the Windows Defender scan. It forces up to 100% usage of the device's Hard Disk Drive (hard drive) and Central Processing Unit (CPU). ...

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Is your laptop or desktop locking up during Windows Defender scans?


Does your laptop or desktop lock up during Windows Defender Scans?

When you check the system performance on an application such as the Process Explorer, is MsMpEng.exe showing excessive usage of the laptop or desktops resources?

Does this cause the device to grind to a slow crawl or lock up by using 80% to 100% of the devices resources?

If any of the above statements are true, then you should read through the following section of this article.


Why is this happening?


The following sections are the methods that Microsoft recommends stopping the MxMpEng.exe file from causing high hard drive and CPU usage on your laptop or desktop.

  • MsMpEng.exe is the core process of the Windows Defender anti-malware application.
  • Windows Defender comes pre-installed on Windows 11 and Windows 10 but is an optional download on older Operating Systems like Windows 7 and 8.
  • This issue with MsMpEng.exe taking 100% of the hard drive and CPU usually occurs when Windows Defender is scanning the laptop or desktop for malware. The Windows Defender scan is getting stuck on a few files while checking malware. When that is happening, it should be restricted or disabled to bring it back to normal use.

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Method I: Ensure that no other Adware, Anti-malware, or anti-virus software is installed or not fully removed


MsMpEng.exe - Its role is to scan files for spyware, and quarantine or remove them if they are suspicious. It also scans your laptop or desktop for known worms, harmful software, viruses, and other such programs.

Note: Best practice is to have only ONE anti-malware, anti-virus, or anti-spyware program on your laptop or desktop at a time. Do Not have multiple programs running or installed simultaneously. These programs conflict and find each other as files to be quarantined and deleted.

Windows Defender comes installed by default with Windows 11 and Windows 10.

That means that any additional software is installed after Windows Defender - Windows defender keeps them from installing or running correctly.

  1. Right-click the Start Icon and choose Control Panel from the menu.

  2. Go to Programs and Features and remove any of these types of programs that are listed there.

Windows Defender does not come installed with Windows 8 and Windows 7.

After installing Windows Defender, Windows defender keeps any new software from installing or running correctly.

If Windows Defender was installed after these other types of software - these software programs keep Windows Defender from installing correctly.

  1. Open the Control Panel from the Start menu.

  2. Go to Programs and Features and remove any of these types of programs that are listed there, including Windows Defender.

  3. Install the program that you want to continue using.

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Method II: Prevent Windows Defender from scanning a specific folder on your laptop or desktop


One reason for the high load is the MxMpEng.exe file scanning its folder. If you have a known folder on your laptop or desktop that is causing Windows Defender an issue, you can get Windows Defender to ignore it.

  1. Click the Start Icon and type Windows Defender. Double-click the icon when it appears in the search list.

  2. Click Settings and select Add an exclusion from the bottom of the window.

  3. Choose Exclude a folder and enter the path of the wanted directory. In this case: C:\program files\windows defender

msmpeng exclusion windows defender

(Figure.1 Add an Exclusion Settings Window)

  1. Open the Windows Defender utility. Open the Tools and Advanced Options sections.

  2. Open Excluded Files and Locations.

  3. Enter the path of the wanted directory. In this case: C:\program files\windows defender

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Method III: Slow the scan by lowering the set affinity of Windows Defender on your laptop or desktop


You can set the MsMpEng.exe file to use a specific processor in the device to avoid high CPU usage. However, it cuts the scan speed of Windows defender and the fan runs slower than usual. Is slow scan speed better for you than having high CPU usage? Apply the following steps to set the affinity in limited mode.

  1. Open Task Manager:

    • Right-click the taskbar and select Task Manager.

    • Right-click the Start Icon, select Task Manager.

    • Click the Start Icon and type Task Manager, click the task manager icon from results.

  2. Go to the Details tab.

  3. Right-click the process name msmpeng.exe and select Set affinity.

msmpeng affinities task-manager

(Figure.2 Set Affinity in Task Manager Window)

  1. Choose the CPU limit that you allow the process to use.

  1. Open Task Manager:

    • Right-click the taskbar and select Task Manager.

    • Press the Ctrl, Alt, and Del keys together for an on-screen menu to appear. Select Task Manager.

    • Type Task Manager on the start menu, click the task manager icon or the Open command from the search results.

  2. Go to the Processes tab.

  3. Right-click the process msmpeng.exe and select Set affinity.

  4. Choose which cores of the CPU that you allow the process to use.

Note: For normal CPU usage, select 50% for MxMpEng.exe (That is one core of a dual-core CPU, two cores of a quad-core CPU, and so on.)

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Method IV: Disabling Windows Defender through group policies on your laptop or desktop


Disabling Windows Defender is a severe answer that solves your issue that is related to high CPU usage.

Note: Your laptop or desktops protection suffers without any anti-virus software installed. If you disable Windows Defender, ensure you have another anti-malware application to install in its place. This can be either free or paid, but ensure you have something that is installed in Windows Defenders place.
  1. Open a Run Window and type gpedit.msc:

    • Press the Windows logo and the R keys together.

    • Open the start menu and select Run.

  2. This opens the Group Policy Editor. (This is only available on Pro and Enterprise editions. There are ways to install it on Home editions, but this article does not cover them.)

msmpeng group-policy windows defender

(Figure.3 The Group Policy Editor)

  1. Scroll down the tree structure on the left of the screen until you get to Computer Configuration. Open it and go to Administrative Templates, then Windows Components. Look for Windows Defender anti-virus.

  2. In the pane on the right of the screen, double-click Turn off Windows Defender anti-virus.

  3. A Properties window opens, choose Enabled, and click Apply and OK to save the change, then close all the windows.

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Last Published Date

29 Jan 2024



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