saveSave this text as a .reg file and execute:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender]
"DisableAntiSpyware"=dword:00000000
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection]
"DisableRealtimeMonitoring"=dword:00000001
thisThis disables only realtime which helps to speed up the computer.
Set the first value to 00000001
to fully disable it.