Windows Defender going crazy

[typographie]

For the past couple of days I've been getting some really nasty intermittent performance issues. I checked Task Manager and found that MsMpEng.exe (Windows Defender) is often chomping away at upwards of 30%+ CPU usage. It does not seem to care what I'm doing at the time. If anything, it seems to happen more when I'm gaming than not. This just randomly started happening a few days ago, it's never been an issue for me before in years of using Windows 10.

 

I've tried several workarounds I found from some Google searching:

• Adding C:\Program Files\Windows Defender (either the entire folder or MsMpEng.exe by itself) to the Windows Defender exclusions list. Didn't change a thing, as far as I can tell.
• Checked Task Scheduler... Most of the Windows Defender options are grayed out and inaccessible to me.
• Tried to Set Affinity and Set Priority for the executable... "Access is denied."
• Tried to terminate Windows Defender through the Services Administrative Tool... again, grayed out, inaccessible.
• I've checked the process path from Task Manager to make sure it's not some sketchy lookalike malware file hiding out in the depths of AppData or something.. nope, it's C:\Program Files\Windows Defender\MsMpEng.exe.
• I tried to start up a manual Full Scan and leave it running over night, in the hopes that that would satisfy its scan-lust for awhile. I'm still having the issue today, so I guess that did nothing.

The only thing that seems to work with any consistency is to go into Windows Defender's settings and turn off Real-Time Protection. But as the description text says, it automatically turns itself back on after a bit. Plus, I shouldn't have to turn it off. It's been fine forever until now.

 

Most of the stuff I've found online about this seems to assume it's normal scanning behavior. This has been going on for like 72 hours at this point, it's had time to complete a full scan tens of times over. Presumably my PC has been doing normal Defender scans all along without issue.

 

Anyone have any ideas? 

[captain_to_fire]

I think Windows Defender is the issue but I could be wrong. I don’t use Windows Defender. 

[johnukguy]

Turn off Windows Defender. It's seriously crap anyway. Use something like Panda or Avast free anti virus and malwarebytes. See if they react the same way.

[typographie]

4 hours ago, johnukguy said:

Turn off Windows Defender. It's seriously crap anyway. Use something like Panda or Avast free anti virus and malwarebytes. See if they react the same way.

I understand that there are probably lots of better options out there for anti-malware, but simply disabling Windows Defender and trying another is something I could've come up with all on my own. I came here in the hopes that someone might be able to take some guesses at what's actually going on with my system; or at least point out a known issue from a Windows update or something that would account for it. For all I know, what Defender's doing may be a symptom rather than a cause of some other problem.

As I said, I've had Windows Defender enabled with the same settings as long as Windows 10 has been out, and it has not behaved in this way until now. Whether or not it is "seriously crap" vs. Product X or Product Y is not really the discussion here.

[johnukguy]

8 hours ago, typographie said:

As I said, I've had Windows Defender enabled with the same settings as long as Windows 10 has been out, and it has not behaved in this way until now. Whether or not it is "seriously crap" vs. Product X or Product Y is not really the discussion here.

Do you honestly not know that Windows Defender has regularly failed certification as even a basic antivirus? It's only just started to pass certification and then only just. The problem here is in fact Windows Defender. If you want to carry on using it then don't whine when others suggest a real alternative that works better. It doesn't matter how long you've been using it, that doesn't change the fact that nobody who knows anything about system protection would use it.

https://www.pcmag.com/article2/0,2817,1926596,00.asp

[typographie]

10 hours ago, johnukguy said:

If you want to carry on using it then don't whine when others suggest a real alternative that works better.

I don't care about Windows Defender and I have no particular attachment to it. I already know it's not ideal system security. Maybe I'll consider alternatives to it after I figure out why my system is behaving unusually, or maybe I won't. Your concerns have been noted, and I'll worry about it later if I ever feel as motivated about it as you are.

 

In this thread, here in the Troubleshooting subforum, I want to discuss why Windows Defender is not behaving for me the way it does for millions of other people, or how it did for me until just a few days ago. I want to actually figure out the nature of the problem before I start switching software and possibly muddying the issue further. You know, "troubleshooting." If you don't have anything to contribute to that discussion, thanks anyway.

[johnukguy]

The 'nature of the problem' is Windows Defender itself, as you will discover.

[bomberblyat]

services.msc write that to windows thingy and disable windows defender

[RumSwift]

18 hours ago, typographie said:

I don't care about Windows Defender and I have no particular attachment to it. I already know it's not ideal system security. Maybe I'll consider alternatives to it after I figure out why my system is behaving unusually, or maybe I won't. Your concerns have been noted, and I'll worry about it later if I ever feel as motivated about it as you are.

 

In this thread, here in the Troubleshooting subforum, I want to discuss why Windows Defender is not behaving for me the way it does for millions of other people, or how it did for me until just a few days ago. I want to actually figure out the nature of the problem before I start switching software and possibly muddying the issue further. You know, "troubleshooting." If you don't have anything to contribute to that discussion, thanks anyway.

He's literally telling you the program itself is the issue.

 

"Windows key + X and select Command Prompt (Admin) and type sfc /scannow and return.  If it repairs system files, run it again until no errors. In case Windows Defender is caught in a loop, consider running it offline. If this does not solve your problem, restore the default settings of Windows Defender Services only per the following tutorial. If the problem still persists, you may have to Refresh Win 8."

 - https://answers.microsoft.com/en-us/protect/forum/all/windows-defender-service-is-using-high-cpu-all-the/314a8a3f-1345-4e5c-80cd-526544bd5741?auth=1

 

Quick Google search. Might not fix your issue but from one search I can tell that it is actually a common occurrence with the program itself.