I am running Windows 10 on a fairly recent laptop. I'm using Avast (free version) as antivirus and before the update, Windows Defender was turned off as it should be in case a third party antivirus is installed.
Yesterday I received a notification of an available update for the OS. I ran the update on shut down, and this morning when turning the computer on, it completed the updating procedure in about 1 hour.
The update, as far as I can tell, restored a lot of bloatware that was installed on the PC at the time of the purchase, installed some additional Visual Studio components and some new applications, and it turned on Windows Defender.
I find this all weird since Avast was (and still is) running fine as usual, but now I have a resource hog (Windows Defender) sucking on my PC resources. Furthermore Cortana is running in the background even though I disabled it...
Why has this thing happened and how can I turn Windows Defender off? Since apparently it has not detected that Avast is running, it somehow turned itself back on again.