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antimalware service executable high cpu usage

Anonymous
2025-07-02T08:17:06+00:00

slow performance

Windows for home | Other | Security and privacy

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

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  1. Anonymous
    2025-07-02T09:37:43+00:00

    Hello Oswald Forster,

    Welcome to Microsoft Community.

    Understood. Based on your description, the issue mainly involves high CPU usage by the Antimalware Service Executable, which is causing performance degradation.

    Regarding Windows Antimalware Service Executable, you can use Group Policy (available in Windows Pro or higher editions) to limit its CPU usage:

    The Antimalware Service Executable is a process of Windows Defender, the built-in antivirus software in Windows.

    Here’s how you can configure it:

    1. Press Win + R to open the “Run” dialog, then type gpedit.msc and press Enter.
    2. This will open the Local Group Policy Editor.
    3. Navigate to:
      Computer Configuration → Administrative Templates → Windows Components → Windows Defender Antivirus → Scan
    4. Double-click on “Specify the maximum percentage of CPU usage during a scan”.
    5. Select “Enabled”, then set the percentage value (according to your needs).
    6. Click Apply, then OK.

    This should help reduce the impact of antivirus scans on your system’s performance.

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    Ian Trinh | Microsoft Community Support Specialist

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  2. quietman7 MVP Alumni 19,695 Reputation points Volunteer Moderator
    2025-07-02T14:01:28+00:00

    It is not unusual to observe high memory usage by the Antimalware Service executable when Microsoft Defender is running a Full Scan, especially while attempting to use the computer during the scan. Until Microsoft Defender service completes this task it will continue to consume high memory and CPU usage. To avoid this issue, run a scheduled scan at a time when you're not using the computer.
     
    If you're not running a scan, according to Ramesh Srinivasan [VM], Volunteer Moderator at Microsoft Answers in this topic..."It's normal to see Defender consuming200-300 MB of memory when no scans are running*. If it consistently uses more Disk I/O and memory, it could be because another process is triggering the on-demand scanner repeatedly.*"
     
    If you're not not running a Full Scan when this happens, try this.
    1. Temporarily disable Real-time protection in Virus & threat protection section.
    2. Open Task manager and check if the memory has returned to normal.
    3. If so, go back and reenable Real-time protection.

    Press the Windows Key + R on your keyboard.

    • In the Run Box, type: windowsdefender://threat/
    • Press OK or Enter.
    • Scroll down and select Manage settings under Virus & threat protection settings.
    • Click on Add or remove exclusions.
    • Select Add an exclusion and then click on Process.
    • Paste the full path of the Antimalware Service Executable location.
    • Click on Add and restart your computer.

    These are some more resources with additional information which address this issue.

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