Share via

Windows Defender Real Time Protection slowing computer

Anonymous
2018-07-24T04:59:37+00:00

I have had my PC since February and in the past couple of days i have been experiencing delays (up to 10 seconds) when browsing the web or opening programs.

After so investigating, I have come to the conclusion that it's Windows Defender.

When I am doing absolutely nothing on my PC and the only thing open is Task Manager, all is fine and the CPU usage is at 0-1%, but whenever I open anything, be it a game, Firefox, Office, etc.... Windows Defender starts using 30%+ of my CPU.

Disabling Real Time Protection stops this happening and everything runs smoothly, so that's clearly the cause. However, I would prefer not to have it turned of for several reasons:

-I want anti-virus protection

-3rd party AV is usually more demanding (and costs money)

-It was fine until the past few days.

I have tried running scans, I have updated windows to the latest updates, but nothing stops the problem other than turning it off.

Is there a way to reinstall just windows defender? Maybe that would work. I don't want to refresh Windows 10 because I have a lot of programs I don't want to have to reinstall.

Windows for home | Windows 10 | Security and privacy

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

0 comments

4 answers

Sort by: Most helpful
Most helpful Newest Oldest
  1. Anonymous
    2018-07-26T22:59:58+00:00

    I made sure my PC was fully up to date (it was), then I did a Full Scan. It took a while but after it was done it had found 1 threat, which I removed.

    I restarted my PC but it still kept happening. After a bit more testing, I discovered it actually only happens constantly when using Firefox. Other apps cause a spike when starting but that's about it.

    I tried uninstalling then reinstalling Firefox, but that never worked. But then I found that by excluding AppData/Roaming/Mozilla and AppData/Local/Mozilla in Windows Defender seemed to fix it. I still don't know why it was going crazy, but at least I can use it again.

    But for some reason, I have to turn off then turn back on RTP every time I restart my PC for it to remember the exclusion.

    4 people found this answer helpful.
    0 comments
  2. Reza-Ameri 45,811 Reputation points Volunteer Moderator
    2018-07-26T14:49:10+00:00

    Try update Windows and run a full system scan with Windows Defender.

    Try update other application.

    If problem persist, open start and search for feedback and open Feedback Hub app and report this issue.

    2 people found this answer helpful.
    0 comments
  3. Reza-Ameri 45,811 Reputation points Volunteer Moderator
    2018-07-27T15:23:28+00:00

    Just for test try uninstall Firefox and see whether problem persist?

    Did you installed Firefox from its official website?

    Try report this issue to Firefox support too.

    0 comments
  4. Anonymous
    2018-07-26T22:33:12+00:00

    Hi Dragon,

    In response to your question about reinstalling Windows Defender.

    I don't think that is possible, but you can do a Repair Upgrade, which will merge

    a new Windows ISO with your current system. The repair upgrade will keep all

    of your files and apps. And you end up with a brand new Windows Defender.

    For peace of mind, you might want to create a recovery drive before proceeding.

    Download a Media Creation Tool from here: https://www.microsoft.com/en-us/software-download/windows10

    Run the tool as an administrator, and select "Create installation media for another

    PC".  After selecting your language, select the media that you want to use. I prefer

    ISO. The USB method had some problem recently. But I think it may be fixed by now.

    If you select ISO, click "save", and the current Windows ISO will download to your

    Documents file. Takes about 35 minutes on a fairly fast internet connection.

    Important: During the repair, when you are asked (What files to keep) ensure that

                      both options are CHECKED in order to keep your Apps and Files intact.

    Find the Windows ISO folder in your Documents file, and right-click it. Select "Properties"

    and on the General tab, ensure that it is set to open with Windows Explorer. Close

    properties. Right-click the folder again and select "Mount". The ISO files are displayed.

    Double-click "Setup" to begin the repair operation.

    Andre has an article depicting this procedure, to which you might like to refer.

    https://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install-winpc/how-to-perform-a-repair-upgrade-using-the-windows/35160fbe-9352-4e70-9887-f40096ec3085

    Just like an installation, it takes a while. And the PC will restart several times. Be patient.

    Regards,  Glen

    0 comments