Windows 10: Windows Defender Full Scan uses way too much CPU and makes computer unusable

This issue started 2 days ago and was completely non-existent before that. When I run a Full Scan in Windows Defender the program uses 100% of my CPU and makes nearly all other programs unusable. When I did this previously it seemed like Defender decreased CPU usage depending on what was needed but now it always uses near 100% of the CPU and slows everything down.This only happens when running a full scan, quick scans never have this problem.Here's a game running with a full scan being run in the background: https://youtu.be/I0K0ia3uhAsHere's the same game without a full scan being run

:)

 

Windows defender advanced scan extreme cpu overload

I routinely do Windows defender advanced scans. Up until about 2 weeks ago, that is.

All of a sudden the scan was completely maxing out my cpu. I wouldn't say it crashed the computer, but if I tried to do the simplest task while it was running, it rendered the machine unusable due to the draining of resources. Not to mention the scan would disappear, but was still running in the background. The only thing I could do at that point was to wait until it was done scanning, or shut down the unit

I found this thread that's about a year old, followed some of the suggestions, but nothing really helps.

I have no problem with the Quick scan.

High CPU usage when Windows Defender perform a Full Scan in Windows 10 - Microsoft Community

Windows Defender is my only virus protection, so there is nothing to create a conflict.

I put my defender installer folders in the excluded list. I changed my power settings from High Performance to Balanced.

I ran chkdsk /scan, sfc /scannow, dism /online /cleanup-image /restorehealth, and a Memory diagnostic. All normal.

Finally, I did a fresh install.

Is anybody else experiencing this?

 

Windows Defender full or custom scan maxes cpu

Hello!

I've been having issues with Windows Defender on Windows 10 for a while now. It started sometime during the summer, though I can't pinpoint the exact date. When I run a full or custom scan, Antimalware Service Executable will quickly start jumping up to
100% cpu and it makes my computer basically unusable for the duration of the scan. It's not a constant 100%, but while it does go up and down it spends a lot of time at or near 100%. It doesn't matter what drive I scan, this issue crops up a few minutes in.
The automatic scheduled scans presumably work alright, since I've never actually noticed them happening.

It's not an issue with background processes, because when Defender is the only thing running it will just hog more %. The highest I've seen it go is 96% cpu for Defender alone. Windows Defender is my only antivirus, so it's not a conflict either.

I've tried googling for solutions and haven't really found anything helpful. I added an exception for MsMpEng.exe, but that did nothing. I can't set an affinity for this process, though some posts suggest that might be normal. I've updated Windows and everything
is the most current version available.

I'd really appreciate any suggestions for resolving this. I need to be able to scan my whole PC, not just a quick or scheduled scan.

 

defender scans

Hi Ian,

Thanks for posting your query on Microsoft Community.

This issue might occur if you have set any task scheduler for Windows Defender.

I suggest you to delete the task for Windows defender and check if it helps.

Follow the below steps:

• 
  Search and open Schedule tasks.
  
• 
  In the left-hand menu, open the Task Scheduler Library, then select
  Microsoft >Windows >Windows Defender.
  
• 
  Double-click Windows Defender Scheduled Scan.
  
• 
  Select the Triggers panel, then select Delete.
  

Hope it helps, reply to us with the status of your issue. We will be happy to assist you.