Windows defender has 100% disk activity in Windows 10

To disable this behavior, try these. For some genius idea, that file is scanning itself. I am sorry but I really can't explain why is that happening. Adding it to the exclusion list, fixed for mines and for my friends. That's how I came to that conclusion. I have also experienced similar situation and this worked.

Anyway, let's fix it!

Open Task Manager, and right click the "Antimalware Service Executable" and choose open file location.

Once you opened file location, you must the copy the directory from the address bar.

Now, go to Windows Defender , go to Settings > Excluded files and locations.

In first box, paste the path and click Add The path will show up on the second box Save changes and your problem must be fixed. Please note that this procedure is a workaround, it reduces the protection, it excludes scanning the mentioned path. If that's not a problem, go ahead and give it a try.

Regards.