Today I noticed that my Windows 8.1 was getting very slow. I decided to take a look at Task Manager where I noticed that AntiMalware Service was using about 70-90% CPU. For some instants, the usage was full, 100%!
This guide explains how to fix this problem and is applicable to integrated Windows Defender in Windows 8.x and to Microsoft Security Essentials in Windows XP, Vista and 7.
By saying this you are already understood AntiMalware Service Executable is a Windows Defender/Security Essentials service, so ending this process is not recommended. Anyway, you won’t be able to end it because is a integrated system process, so you probably will get access denied exception.
Why does it happen?
It’s something ridiculous. I will try not be ironic at all … because I really want to.
In the Task Manager (pictures below are from Windows 8.x but the process is identical in 7 and older), if you right click AntiMalware Service Executable, you can open the file location.
Now, go to Windows Defender or Microsoft Security Essentials (search for it on Start Menu), go to Settings < Excluded files and locations