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Disable Defender Antivirus service high-priority startup

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Works with Windows 10 and 11Works with Windows Vista, XP, 7, 8, 10, 11, and Windows Server 2008 or newer.
  • Single actionThis page belongs to a script, containing basic changes to achieve a task.
  • Windows onlyThis script improves your privacy on Windows
  • Impact: MediumSystem Functionality Loss Risk: Moderate
    This action improves privacy with minimal impact when you run the recommended script.
    This action improves privacy with some impact when you run the recommended script.
  • Batch (batchfile)These changes use Windows system commands to update your settings.
  • Fully reversible

    You can fully restore this action (revert back to the original behavior) using this website.

    The restore/revert methods provided here can help you fix issues.

Overview​

This script configures Defender Antivirus to start with a lower priority.

By default, Windows runs the Defender Antivirus service (also called the Antimalware Service 1) with normal priority 2 3 4 5. This script changes the startup priority to low 2 3 4 5.

This enhances privacy by reducing background scanning and potentially limiting data collection during Windows startup. It may improve system performance by reducing resource usage for the antivirus during startup 2 3 4 5.

Lowering the priority may delay antivirus initialization, potentially leaving a brief window where the system is less protected. However, MITRE, a leading cybersecurity organization, does not consider this a security vulnerability 5.

Caution

This action may delay antivirus protection initialization.

Technical Details​

This script sets the following registry keys to configure Group Policy Objects (GPO):

  • For recent Windows versions: HKLM\Software\Policies\Microsoft\Windows Defender!AllowFastServiceStartup 2 4
  • For older Windows versions: HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware!AllowFastServiceStartup 3
  1. Security Trade-off

    This action prioritizes privacy over certain security features. It's not recommended and should only be used by advanced users after understanding its implications.

    Increased Privacy

    Enhanced privacy through reduced data collection and tracking

    Decreased Security

    Some security features will be disabled or limited

    This script can be reversed, this allows you to restore the default system security.

  2. Use with Caution

    This script is only recommended if you understand its implications.

    Some non-critical or features may no longer function correctly after running this script.

    This script can be fully reversed to restore changes if something goes wrong.

Sources
PrivacyLearn.com maintains strict sourcing standards for accuracy, integrity and up-to-date content. Our content relies on authoritative sources including vendor documentation, industry standards, and verified research. Learn more about our verification process and quality standards in our editorial standards page.

Apply Now​

Choose one of three ways to apply:

Download script​

Download and run the script directly
  • No app needed
  • Offline usage
  • Easy-to-apply
  • Free
  • Open-source
Help

How to apply or restore "Disable Defender Antivirus service high-priority startup" using script​

  • ≈ 2 min to complete
  • Tools: Web Browser
  • Difficulty: Simple
  • ≈ 5 instructions
  1. 1

    Download

    Download the script file by clicking on the   Apply protection  button above.
    Use   Undo protection button above to restore changes.
  2. 2

    Keep the file

    If warned by your browser, keep the file.
  3. 3

    Open

    Open the downloaded file.
  4. 4

    Exit

    Once it's done, press any key to exit the window.
  5. 5

    Restart

    Restart your computer for all changes to take effect.

Apply with privacy.sexy​

Guided, automated application with safety checks
  • Recommended for most users
  • Includes safety checks
  • Free
  • Open-source
  • Popular
  • Offline/Online usage
Open privacy.sexy
Help

How to apply or restore "Disable Defender Antivirus service high-priority startup" using privacy.sexy​

  • ≈ 3 min to complete
  • Tools: privacy.sexy
  • Difficulty: Simple
  • ≈ 4 instructions
privacy.sexy is free and open-source application that lets securely apply this action easily with more advanced options.
  1. 1

    Open or download

    Open or download the desktop application
  2. 2

    Choose script

    1. Search for the script name: Disable Defender Antivirus service high-priority startup
    2. Check the script by clicking on the checkbox.
  3. 3

    Run

    Click on ▶️ Run button at the bottom of the page.

    This button only appears on desktop version (recommended). On browser, use 💾 Save button.

Run commands​

Copy and run commands manually Requires technical knowledge
Apply changes
:: Set the registry value: "HKLM\Software\Policies\Microsoft\Windows Defender!AllowFastServiceStartup"
PowerShell -ExecutionPolicy Unrestricted -Command "$registryPath = 'HKLM\Software\Policies\Microsoft\Windows Defender'; $data =  '0'; reg add 'HKLM\Software\Policies\Microsoft\Windows Defender' /v 'AllowFastServiceStartup' /t 'REG_DWORD' /d "^""$data"^"" /f"
:: Set the registry value: "HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware!AllowFastServiceStartup"
PowerShell -ExecutionPolicy Unrestricted -Command "$registryPath = 'HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware'; $data =  '0'; reg add 'HKLM\SOFTWARE\Policies\Microsoft\Microsoft Antimalware' /v 'AllowFastServiceStartup' /t 'REG_DWORD' /d "^""$data"^"" /f"
Help

How to apply or restore "Disable Defender Antivirus service high-priority startup" using commands​

  • ≈ 2 min to complete
  • Tools: Command Prompt
  • Difficulty: Medium
  • ≈ 3 instructions
 View step-by-step guide with screenshots
  1. 1

    Open Command Prompt

    Open Command Prompt as Administrator.
  2. 2

    Copy code

    Copy the code:
    Copy Apply Code Copy Revert Code
  3. 3

    Paste & run

    Paste the commands into Command Prompt and press Enter to run.

    Some changes require a system restart to take effect

Similar Guides​

Wider Goal​

Guides below includes this guide to achieve a wider goal.See other more general settings that includes this one as one of its actions.
These plans combine multiple privacy settings, including this one, for stronger protection.
This category disables the Defender Antivirus service and its related components. This service is also referred to as Microsoft Defender Antivirus Servic...

— Disable Defender Antivirus service

Same Goal​

Other guides in Disable Defender Antivirus service See settings that are in the same category as this guide.
Using other actions in the same category may help you achieve your goal better.
See all 10 guides

About the Creators​

These people have authored this documentation and written its scripts:

  • Avatar of undergroundwires. The creator of PrivacyLearn and privacy.sexy. Black and white portrait showing a person wearing a polka dot tie and suit jacket, reflecting the professional expertise behind the privacy protection tools.
    • Certified security professional
    • 7+ years experience securing banks
    • Open-source developer since 2005
    • EU advisor, Public Speaker, Moderator
    • Hundreds across the globe
    • Testers, reviewers, developers
    • Companies, military agencies
    • Community since 2017
About Us

Reviewed By​

This guide has undergone comprehensive auditing and peer review:

  • Expert review by undergroundwires​

    • Verified technical accuracy and editorial standards
    • Assessed system impact and user privacy risks
    • Audited and verified using automated security tests

  • Public review by large community​

    • Privacy enthusiasts and professionals peer-reviewed
    • Millions of end-users tested across different environments
    • Audited and verified using third-party security software

History​

We continually monitor our guides, their impact and other potential privacy options. We update our guides when new information becomes available. On every update, we publicly store who made the change, what has been changed, why the change was made and when the change was made.

Review Change History Our Change Process