That may be your issue.
MSFS does need, and makes accomodations for Windows updates, and vice versa.
If you don’t have Windows up to date, you most probably will have issues.
Scenery poping is caused by the extremely low LOD distance switching currently implemented in game. This is likely to happen to almost all small size objects as the current LOD switching is a joke and it´s implemented globally according to object´s size in the screen. There´s nothing in the Nvidia drivers nor in its settings that handles LODs and it has been like that for decades. That kind of setting is exclusively managed by games own graphical configuration parameters and the hardcoded settings implemented by devs.
Changing and erratic fps together with stuttering or freezes are caused by slow memory management inplemented in game. This is expected to be fixed by SU15. You may find some freezes during first time shaders generation after a new driver update but this would only happen during the first flight as afterwards shaders are reused.
By the way, existing shaders are automatically deleted by Nvidia installer upon any driver update, which usually happens quite frequently, so you don´t need to take care of deleting them manually.