Microsoft Security Essentials MsMpEng.exe using high CPU Time 32

Microsoft Security Essentials MsMpEng.exe – Antimalware service executable using high CPU Time

I have Windows 7 Ultimate x64, but I think this might be problem in any version. I keep having issues with Microsoft Security Essentials MsMpEng.exe using high CPU Time and hogging the cpu.  Basically, using a large amount of resources, like 100%!  It’s eating the CPU time and a lot of memory.  The system will work just fine, even after running for hours, when suddenly the system slows to a crawl, almost to the point I have to reset the system.  I finally narrowed the culprit to MsMpEng.exe, the scanner for MSSE (Microsoft Security Essentials).

Good news is, I think the cpu hog problem is solved!

I found a link on a Google search about adding exclusions, which I suspected would be a problem for things like my backup programs.  I added Crashplan and Syncback programs already, but what I found in that Google search was that you need to add the MSSE directories in C:\ProgramData to the exclusion list.  WHAT!!???  Are you kidding me?  MSSE doesn’t already exclude itself?  Come on MS!!  I really like MSSE,  but that’s pretty stupid.

I went ahead and added the directories below to MSSE exclusions:
(Be sure you set your system to Show Hidden Files in Windows Explorer, because C:\ProgramData is hidden in Windows 7, and so is the “All Users” profile folder in XP.)

– – For Windows 7 – –

C:\ProgramData\Microsoft\Microsoft Antimalware
C:\ProgramData\Microsoft\Microsoft Security Essentials
C:\Program Files\Microsoft Security Essentials

– – For Windows XP – –

C:\Documents and Settings\All Users\Application Data\Microsoft\Microsoft Antimalware
C:\Documents and Settings\All Users\Application Data\Microsoft\Microsoft Security Essentials
C:\Program Files\Microsoft Security Essentials


1. As stated above, make sure you have enabled/showed hidden files.
2. You may need to search your system for “Mirosoft Antimalware” or “Security Essentials” if you do not see the folders listed above.
3. I have not tested this in XP and don’t know the exact locations, so if you don’t see, do a search on your computer.
4. Thank you to several commenters for the extra information regarding XP and other possible locations!


Now, for a couple days, I have had no more issues!!!  We’ll see in a week if it really fixes it.  That’s an easy fix, but completely annoying!  I still like MSSE regardless.  It’s not perfect, but I’d rather have it than anything else.

I am curious to know if anyone else found this fix to work?

Note:  I do recommend people run a manual scan with MalwareBytes and SuperAntispyware once in a while, along with the real time scanner in MSSE.  MSSE didn’t catch a recent trojan at one of my clients, same one was blocking MalwareBytes too.  Only SuperAntispyware cleaned the system properly.

EDIT 02/10/2010:

It’s been about a week and a half, still working fine! It appears that this fixed the problem!

EDIT 02/23/2011:

I have also seen a new setting to scan only when the computer is not in use, which has also helped in some cases. Check out my newer post:


EDIT/NOTES 3/13/2013:

Some very helpful visitors have commented about the paths that may have changed on some systems. I am guessing that’s due to newer versions released since this post.  Anyway, check these paths in your system as noted in the comments.  This person had an XP Home sp3 system.

1) C:\Docs and Settings\All Users\Application Data
\Microsoft\Microsoft Antimalware
2) C:\Docs and Settings\All Users\Application Data
\Microsoft\Microsoft Security Client
3)   C:\Program Files\Microsoft Security Client

Thanks to all of you that have visited and provided “constructive and helpful” comments.