Windows 10: My CPU is being used 100% because of windows defender

so my computer was running slow so i got on task manager and low and behold Antimalware Service Executable keeps on using 10% - 90% of my CPU i tried ending the task i cant, i tried excluding it sometimes works but not always because iturn off my computer when not in use

:)

 

100% CPU Usage after Windows 10 upgrade

Hello Aaron,

Thank you for posting on Microsoft Community. We regret the inconvenience caused and will assist you in resolving the issue.

Most of the time, computers only use a small fraction of their CPU power. In fact, many computers use less than 5% of their CPU most of the time. When you open an application, play a video game, or encode media file, the CPU usage will rise or spike temporarily.
Once the CPU intensive process completes, the CPU usage should once again drop down to lower level. Most applications will not use up more than 50% of your CPU for an extended period of time. However, some programs and system processes can use up a large amount
of CPU without you even knowing it. This may happen if a program gets stuck in an infinite loop or encounters an unexpected error.

I suggest you to perform Safe mode and Clean boot procedures on the PC by following the steps below.

Step 1: I suggest you to boot your PC in Safe mode by following the steps from the link below and check if the issue is resolved.

Safe mode is a diagnostic mode that starts your computer with limited drivers necessary to run Windows. The words
Safe Mode appear at the corners of your monitor to identify which Windows mode you are using.

Expand the options to boot into Safe Mode:

http://windows.microsoft.com/en-in/windows-10/start-your-pc-in-safe-mode



Reboot the PC to exit from Safe mode.

To know more about Safe mode, following is an article on
Windows Startup Settings (including safe mode) (Applies to Windows 10 also):

http://windows.microsoft.com/en-us/windows-8/windows-startup-settings-safe-mode

Step 2: If the issue persists, perform Clean boot on your PC by following the steps from the link below and check if the issue is resolved.

Putting your system in Clean Boot state helps in identifying if any third party applications or startup items are causing the issue.

I suggest you to perform clean boot by following the steps from the link below and check if the issue is resolved.

You can open the system configuration window in Windows 10:

a. Using run command.

• • Press Windows Key + R keys on the Keyboard.
  • Type msconfig.msc and press Enter.

b. Using Cortana.

• • Press Windows icon key on the keyboard and type msconfig.
    
  • Select the top most search result.
    

Follow the steps from 3 under How to perform a clean boot
for Windows 8.1 and Windows 8 from the link below (The steps for clean boot suggested in the link below for
Windows 8/8.1 is applicable for Windows 10 as well):

https://support.microsoft.com/en-us/kb/929135

Disclaimer: Start the computer in normal mode refer the section,
How to reset the computer to start normally after clean boot troubleshooting
from the link above.

Write to us with the status of the issue on the same post for further assistance. Your reply is most important for us to ensure we assist you accordingly.

Thank you.

 

Windows Defender - high CPU and disk usage

Thank you very much for your quick response. I've taken all steps you suggested. This is the outcome:

• Add a process exclusion
  
  Unfortunately, this didn't work. I added both a path and a process exclusion now.The task scheduler for
• Defender looks like this for me:
  
  
  
  

• It seems no Defender tasks have run since June 30th, yet the process continues to hog the CPU
• I re-ran SFC /scannow. SFC could not find any integrity violations
• I tried disabling behaviour monitoring. The setting did not persist across a reboot, and turning it off did not make a difference while my system was still running.
  
  
  This was the output for Powershell:
  
  

PS C:\Windows\system32> Set-MpPreference -DisableBehaviorMonitoring $True

PS C:\Windows\system32> Get-MpPreference | findstr "Behavior"

DisableBehaviorMonitoring : True

PS C:\Windows\system32>

• Scanning for viruses and leftover antivirus software. This was interesting (yet unfruitful):
  
  Neither Kaspersky nor Emisoft could find any threats. MalwareBytes did find 5 executables in my temp folder, although Virustotal.com reported no danger for the files. This could mean it's a false positive, but I removed all traces of them anyway.
  
  It also found two installers (PUPs) for a Spigot toolbar, I removed those as well. They probably came with some free software package, I try to prevent installing toolbars.
• In installed AVG Anti Virus (the free version). When I rebooted after the installation, Defender was still running and taking up 25-30% of my CPU. I disabled Defender using the Group Policy editor and the service finally stopped.

AVG works for me, but like most free anti virus programs it's full of ads and "free offers" and fishy SSL/TLS interception ("web protection").

I'd like to keep using Windows Defender because it's neatly integrated into Windows 10, doesn't take a lot of resources and doesn't show annoying ads.

I hope anyone can suggest another way to fix this weird Windows Defender problem.

 

Windows 7 home upgrade to Windows 10 start up looping on Windows Defender using 100% CPU

Windows 7 home upgrade to Windows 10 start up looping on Windows Defender using 100% CPU and the screen is blinking. Can not enter any commands. Can not stop any of the services that are causing the looping. How can this be fixed?