Antimalware Service Executable is Causing High CPU Usage. What Should I do?

The Antimalware Service Executable is a background process within Windows that manages Windows Defender. It has been around since Windows 7 and should run quietly in the background. So quietly that you shouldn’t even know it is there. Unfortunately, it has a tendency to take over when it shouldn’t. This results in anything up to 80% CPU utilization. If your Antimalware Service Executable is causing high CPU usage, here is how to fix it.

As mentioned, Antimalware Service Executable is part of Windows Defender. It is the part that delivers Real-Time Protection and monitors your computer for nefarious code or anything that can do it harm. It usually triggers when you use your network card or plug in a USB drive as the real time aspect needs to work quickly.

What should happen is that the Antimalware Service Executable initiates as soon as your computer enters idle state. Then, when you do something to bring it out of idle, the service should stop and wait until the next idle state. Sometimes, this process goes awry and doesn’t correctly recognize when the computer is no longer idle. Which is where high CPU usage happens.

There are two main ways to stop Antimalware Service Executable causing high CPU usage. The first is to change the way schedule scans works and the second is to disable Windows Defender altogether.

Change the Antimalware Service Executable scan properties

The simplest way to stop Antimalware Service Executable hogging your CPU is to change the way it works.

1. Navigate to Control Panel, Administrative Tools and Task Scheduler.
2. Navigate to the Library in the left pane, then Microsoft, Windows, Windows Defender.
3. Highlight ‘Windows Defender Scheduled Scan’ in the center panel and click Properties in the lower right panel.
4. Uncheck any boxes that are ticked in the window that appears. You should see ‘Start the task only if the computer is idle for:’ ‘Start the task only if the computer is on AC power’ and other options. Some or all of them will be selectable.

This method should stop the scheduled scan taking over when you bring your computer out of idle but won’t stop Windows Defender working in other cases.

Disable Windows Defender

Personally, I don’t use Windows Defender. There are much better and much more competent malware scanners and antivirus programs out there. Many of them are free too and I use a couple of them in a multi-layered approach. You should only undertake this step if you have other protections in place.

1. Install a competent and trusted third-party antivirus and/or malware scanner.
2. Right click an empty section of your Task Bar and select Task Manager.
3. Select the Services tab and click the Open Services text link.
4. Find the three Windows Defender services, stop them and either disable or switch to Manual.

That will definitely stop the Antimalware Service Executable causing high CPU usage!