How to reduce Microsoft Security Essentials load on your system

Martin Brinkmann
Jan 4, 2014
Antivirus, Tutorials

Microsoft Security Essentials is a free security product by Microsoft for Windows XP, Vista and Windows 7.  While that is a good thing, it is also one of the weaker programs in terms of protection.

A recent test on AV Test for example gave it a 0.5 of 5 protection rating, the lowest of the test. And tests on AV Comparatives look as grim.

Still, it appears to be a highly popular choice for users of those systems, likely because it is produced by Microsoft, and because it is easy to use.

Our suggestion would be to switch to another product, like Avira Antivirus, which is also available as a free version.

If you are using Microsoft Security Essentials and noticing that it impacts your PC's performance, especially during scans, then you may be interested in the following tip to reduce the load that the software has on your system.

microsoft security essentials reduce load

Here is what you need to do to achieve that:

  1. Open Microsoft Security Essentials on your PC and switch to the Settings tab in the program interface.
  2. The first thing is to change the maximum cpu cycles that the program may use during scans. The value is 50% by default, which you may want to reduce to 10% instead. While this may prolong the overall scan time, it ensures that resources can be used elsewhere during scans.
  3. What you may also want to consider is changing the day and time of the scan. If you do not want the program to scan your PC each Sunday at around 2:00 AM, change that to a day and time that better fits your work schedule.
  4. MSE will only start scans if your PC is on but not in use, and I'd recommend you keep that setting enabled.

Side-tip: If you want scans to complete faster, remove the "limit cpu usage during scan" check-mark to achieve that.

The second thing that you can do is change the process priority of the msseces.exe process in Windows. Tap on Ctrl-Shift-Esc to open the Task Manager, switch to processes, and find the process listed here.

Right-click on it and select Priority > Below Normal or Low instead. Note that this is only valid for the current session.


If you want the change to be permanent, download a free program like Prio for that. You can use Prio to set the process priority of any process to another value, and have it retain that new value even between sessions.


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  1. Richard Steven Hack said on January 5, 2014 at 6:08 pm

    My comment was marked as spam? Seriously? Because I edited it?

    1. Martin Brinkmann said on January 5, 2014 at 6:22 pm

      WordPress is strange, at times.

  2. Richard Steven Hack said on January 5, 2014 at 6:06 pm

    Yes, I had a client with the same issue – Security Essentials chasing its own tail. It caused a major CPU spike on her system.

    I assume that the reason they do this is to protect the program from itself being compromised by malware, which does happen to AV programs occasionally.

    Given that most of the major AV programs are doing poorly at detecting new malware, using a weak detector like Security Essentials is a bad idea. “Real world” results are likely to be worse than any AV test.

  3. Straspey said on January 5, 2014 at 3:31 pm

    I was recently experiencing an extreme example of this problem – with a very high CPU usage to the point where I could hear my hard disk working very hard.

    When I opened task manager and looked at the process list, I noticed that there was a file which was using abut 50% of the CPU:


    My first inclination was to just try and “end” the process, to see what happens – but I was denied and prevented from doing so.

    So I then ran a Google search and found this link, which provided the explanation and solution:

    Open MSE – Click on Settengs and then, from the list on the left, choose “Excluded files and locations”

    Browse to C:/Pprogram Files/Microsoft Security Client/MsMpEng.exe and add it to the list.

    Click on Save Changes and close the program.

    Apparently, MSE sees its own process as something which needs to be closely monitored — almost like a puppy dog trying to bite its own tail – and this adjustment relieves the issue.

    As far as I can tell – and from the explanation on the link above – this configuration does not interfere with the proper functioning of MSE – because if it did, the configuration would fail – just like it did when I tried ending the process in Task Manager.

    It’s been a few weeks now, and I have not experienced that constant high CPU usage associated with MSE — while at the same time, I have noticed it happening on occasion when the process was being called normally.

    Give it a try – and I would be very interested to hear what Martin thinks about this.

    Happy New Year to All

  4. GK said on January 5, 2014 at 2:34 pm

    Yes please avoid MSE/Defender. Its filter driver causes a significant hit in CPU performance and disk I/O. I recommend using Avast or Avira’s free versions. Better protection, lighter on resources.

  5. sagar nandwani said on January 5, 2014 at 1:38 pm

    Is the percentage one select to be the amount of CPU which MSE is allowed, or which one wishes to reserve for other applications??
    Obviously at 50% it doesn’t matter, does it, but in any other case, it does.

  6. Richard said on January 4, 2014 at 10:54 pm

    I am skeptical of AV test comparisons. The reasons for my skepticism are many. Perhaps the most meaningful one is that it is impossible to re-create real world experiences in a lab. IMPOSSIBLE!

    I have used MSE for years. It is fine. Typically, other free AV products have a much heavier footprint on systems. They also have a more intrusive UX than MSE. They perform their AV function no better.

    BTW, the reason you can’t install MSE in Windows 8/8.1 is because the version of Windows Defender that is incorporated into the OS includes MSE.

  7. Ramesh Khanna said on January 4, 2014 at 10:15 pm

    I understand S E isn’t available for Win8/8.1 because microsoft thinks defender on 8 is strong enough to not need S E. how does defender compare with other security programs?

    1. Martin Brinkmann said on January 4, 2014 at 10:16 pm

      Not good as well.

      1. JohnP said on January 5, 2014 at 4:58 am
  8. Boris said on January 4, 2014 at 5:40 pm

    Hm, my friend is having problems with major slowdowns on her computer from time to time. And incidentally I installed MS Essentials on her computer. This could be a problem.

  9. imu said on January 4, 2014 at 5:00 pm

    Martin, did you hear anything good about Sophos’ UTM Firewall Home Edition? I would love to see your review on this one but I have no idea whether this can be run in VM so in case you have no spare machine to test it then this ain’t gonna happen I know.

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