High CPU usage from Windows Defender

TotesforRealTom said:

I finally fixed my problems after weeks of my laptop being crippled.

The issue appeared to be as others were saying, a broken database file.

To remove it I had to:

1. Decrypt my hard drive
2. Create a Ubuntu boot USB
3. Change my hard drive mode from RAID to AHCI in BIOS
4. Boot from USB
5. Rename the database files as per previous posts
6. Change the disk type back to RAID in BIOS
7. Boot Windows again

What a freaking nightmare...

Deleting the database files worked for me but there is an easier way:

1) Use group policy editor to Turn off Windows Defender (there are many links which show how to do this)
2) Open a powershell as Admin (right click start menu to see this option quickly)
3) Go to the C:\ProgramData\Microsoft\Windows Defender\Scans directory
4) Delete the mpengine* and mpcache* files
5) re-enable via Group policy editor - those file will be recreated but it seems to solve the problem

This fixed the CPU usage issue for me - it was using constantly about 35% CPU for me slowing everything down. Now it usually 1 or 2 % CPU...

High memory and CPU usage by TrustedInstaller, huge CBS.log files and growing.

You may want to check this link from MS. Nothing to loose.

https://answers.microsoft.com/en-us/...b-7539ec0d6691

OH MY GOD,

I can't believe how fast my Laptop is right now after uninstalling "Microsoft Security Essentials" and installing "Avast" antivirus on my "Windows 7 Professional x 64 bit"!

I really still can't believe that "Microsoft Security Essentials" was the culprit for my Laptop slowness for over 1 to 2 months! (problem started from June!)

I was already thinking that my relatively new purchased Laptop was already malfunctioning and I was already thinking on replacing it!

Shame on you Micro$oft, 2 MONTHS ? 2 MONTHS and you still didn't fix this bug yet?

I am\was a 8 years "Microsoft Security Essentials" user, but "This Is It", I will never ever use it again! NEVER EVER!

samster said:

Deleting the database files worked for me but there is an easier way:

1) Use group policy editor to Turn off Windows Defender (there are many links which show how to do this)
2) Open a powershell as Admin (right click start menu to see this option quickly)
3) Go to the C:\ProgramData\Microsoft\Windows Defender\Scans directory
4) Delete the mpengine* and mpcache* files
5) re-enable via Group policy editor - those file will be recreated but it seems to solve the problem

This fixed the CPU usage issue for me - it was using constantly about 35% CPU for me slowing everything down. Now it usually 1 or 2 % CPU...

You can also skip group-policy: Just open Windows Defender Security Center and disable Realtime-Protection. The rest's still the same.

Pinky25 said:

You can also skip group-policy: Just open Windows Defender Security Center and disable Realtime-Protection. The rest's still the same.

Are you sure that just disabling real-time protection allows for deleting those files? I'd be surprised if it did, I think you need to actually disable Defender altogether to be allowed to delete.

But I may be wrong, I haven't tested.

Ah, you're right. Sorry.

Retested, and it doesn't work. Seem's I've done it differently the time before.

So... stick with gpedit.

Pinky25 said:

Ah, you're right. Sorry.

Retested, and it doesn't work. Seem's I've done it differently the time before.

So... stick with gpedit.

Or use Process Hacker or similar app to kill "Antimalware Service Executable" process.

Settings/Privacy/General (change privacy options/ turn All OFF
Settings/Privacy/Windows Permissions/ turn All OFF
Settings/Privacy/App Permissions/ turn All OFF
Restart your PC