Antimalware Service Executable High Memory Usage: Causes, Fixes & Optimization Guide

Introduction

If you are experiencing slow system performance, high CPU, RAM, or disk usage on your Windows PC, you might have noticed a process called Antimalware Service Executable consuming excessive system resources. This process is part of Windows Defender (Microsoft Defender Antivirus) and plays a crucial role in protecting your system from malware and security threats.

However, when Antimalware Service Executable high memory usage becomes a persistent issue, it can slow down your computer and cause frustrating lag. In this guide, we’ll explore why this happens and how to fix it.

What Is Antimalware Service Executable?

The Antimalware Service Executable (MsMpEng.exe) is a core component of Windows Defender, responsible for:

• Real-time scanning of files, programs, and downloads for potential threats.
• Automatic updates to keep virus definitions current.
• Scheduled full system scans to detect and remove malware.
• Background monitoring to prevent unauthorized access.

Since it operates in real-time, it can consume high CPU, RAM, and disk usage, especially during a full scan or update.

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Why Does Antimalware Service Executable Use High Memory?

Several factors can cause Antimalware Service Executable high memory or CPU usage:

1. Real-Time Protection Consuming Resources

• Windows Defender runs continuous background scanning, leading to high memory usage.

2. Full System Scan Running in the Background

• If a scheduled full scan is running, it may hog CPU and RAM, slowing your PC.

3. Windows Defender Conflict with Other Antivirus Software

• Running third-party antivirus software alongside Windows Defender can cause conflicts and increased resource usage.

4. Large Files Being Scanned

• If you frequently download or open large files, Windows Defender takes longer to scan, consuming more memory.

5. Corrupt or Outdated Virus Definitions

• If Windows Defender has corrupt or outdated virus definitions, it may loop in the background, using excessive resources.

6. Windows Defender Scanning Its Own Directory

• Sometimes, Defender scans its own directory, leading to excessive CPU and memory consumption.

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How to Fix Antimalware Service Executable High Memory Usage

Here are proven methods to fix high memory, CPU, and disk usage caused by Antimalware Service Executable:

Method 1: Disable Real-Time Protection (Temporary Fix)

Disabling Real-Time Protection can immediately reduce CPU and memory usage, but it lowers your system’s security.

Steps:

1. Press Windows + I to open Settings.
2. Go to Privacy & Security → Windows Security.
3. Click Virus & threat protection.
4. Under Real-time protection, toggle Off.

🛑 Note: This is a temporary fix—Windows Defender will automatically re-enable protection after some time.

Method 2: Change Windows Defender Scheduled Scans

Windows Defender runs automatic scheduled scans that can cause high CPU and memory usage. Adjusting the scan frequency can help.

Steps:

1. Press Windows + R, type taskschd.msc, and hit Enter to open Task Scheduler.
2. Navigate to Task Scheduler Library → Microsoft → Windows → Windows Defender.
3. Right-click Windows Defender Scheduled Scan and select Properties.
4. Go to the Conditions tab, uncheck:
   • Start the task only if the computer is idle
   • Start the task only if the computer is on AC power
5. Click OK to save changes.

This prevents Defender from running background scans when you’re actively using the PC.

Method 3: Limit MsMpEng.exe CPU Usage via Group Policy Editor

You can set a CPU limit to stop Antimalware Service Executable from using too much memory.

Steps:

1. Press Windows + R, type gpedit.msc, and press Enter.
2. Navigate to Computer Configuration → Administrative Templates → Windows Components → Microsoft Defender Antivirus.
3. Locate Specify the maximum percentage of CPU utilization.
4. Enable it and set the value to 50% or lower.
5. Click Apply → OK.

This will reduce CPU usage but still allow Windows Defender to function.

Method 4: Add Windows Defender Exclusions

To prevent Windows Defender from scanning its own files, add an exclusion for MsMpEng.exe.

Steps:

1. Open Windows Security → Virus & threat protection.
2. Scroll down to Exclusions and click Add or remove exclusions.
3. Click Add an exclusion → Select Process.
4. Type MsMpEng.exe and click Add.

This prevents Defender from overloading your CPU by scanning its own files.

Method 5: Use a Lightweight Third-Party Antivirus

If Windows Defender continues causing high memory usage, you can disable it and use a lightweight antivirus alternative like:

• Bitdefender Free
• Avast Free Antivirus
• Malwarebytes

To disable Windows Defender permanently:

1. Press Windows + R, type regedit, and hit Enter.
2. Navigate to:
   HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
3. Right-click and create a DWORD (32-bit) Value named DisableAntiSpyware.
4. Set its value to 1 to disable Windows Defender.
5. Restart your PC.

🛑 Note: Disabling Windows Defender completely removes built-in protection, so only do this if you have another antivirus installed.

Final Thoughts

While Antimalware Service Executable is essential for Windows security, its high memory usage can slow down your system. By adjusting scheduled scans, setting exclusions, or limiting CPU usage, you can optimize Windows Defender without compromising security.

If the issue persists, consider a lightweight third-party antivirus to keep your PC secure while freeing up system resources.