Windows 10: Windows Defender slowing everything

We have had 4-5 users over the last 2 business days reporting extreme system slowness all of a sudden. This appears to be cause by the ‘antimalware service executeable’ in task manager, using high CPU and Disk write capacity (up to 150MB/s). This makes our affected laptops and desktops almost entirely unusable.



We’ve tried:

• Updating defender
• Disabling defender (in regedit)
• Killing the process (unable to kill it)
• Excluding defender install directories from defender scans
• Running full system scans
• Running in safe mode (stops it happening, but only in safe mode)

Considerations:

• Event viewer shows issues with some of our GPO’s pushing to systems, but the issue persists with systems that are off the domain.
• No clear indication of what defender is actually trying to do on the system.
• Windows is up to date on 1709, we’re not rolling out 1806 to all users as standard currently.
• Not everyone is having this issue, it only seems to affect random users.
• More and more users are starting to report it.

:)

 

windows defender runs slow

Hi Thomas,

Thank you for posting your query in Microsoft Community.

I understand the inconvenience you are facing currently. Let me help you in resolving the issue.

I would appreciate if you can provide us the following information to help us understand the issue better.

• Have you installed any third party security application in your system, apart from Windows 10?
  
• What is the make and model of your computer?

I would like to inform you that this issue might occur, if the Windows defender is scanning too many junk or malware effected files in the system. As of now,
I suggest you to run System maintenance task and check if it helps.

The Run maintenance task checks issues that might slow down your computer's, such as how many users are currently logged on to the computer and whether multiple programs are running at the same time.

Follow the below steps.

• 
  Press Windows + X on the keyboard.
  
• 
  Select Control Panel.
  
• 
  Select Troubleshooting.
  
• 
  Click on Run maintenance task under
  System and Security.
  

For more information, refer to the below link:

http://windows.microsoft.com/en-US/windows/windows-defender-offline-faq

Hope the information helps. Keep us posted on Windows related queries and we will be happy to assist you further.

 

window defender

• • • 
      You will want to print these instructions for offline reference -
      

IMPORTANT => DON'T SKIP ANY STEP perform all Steps in one uninterrupted session - If a Step says to reboot
reboot.

Problems starting Windows Defender in Windows 8/8.1/10

Pləase let us know what fixes the problem or if the pяoblem remains.

• • • 
      `~`
      

 

Windows Defender problem

Hi Ernst,

To troubleshoot this issue, we suggest that you check the Windows Defender service if it's running. If you are using a third party spyware/malware program, it may disable the Windows Defender service. To do this, please follow the steps below:

• Press Windows + R key.
• Type services.msc.
• Right-click Windows Defender service and click
  Start.

Let us know the result.