Right.
The problem fixed itself.
Just today.
Turned my PC on, launched the game, the resolution setting has defaulted, Running in fullscreen 720p, changed it to my native 1080p, works flawlessly, like the problem had never occured.
Nothing changed about my PC overnight, there where no updates, no windows updates, no driver updates.
It just decided to be nice.
I have yet to try a large mod though.