Weird. There is definitely something going on. You’re troubleshooting methodology is sound. Back right after WU6 I experienced game breaking FPS drops on the ground, during take offs and on approach and landings (single digit FPS and multi second stutters). I describe it in the following thread link (several described very similar symptoms)
Although your not describing exactly this, it feels like it may be related? I don’t know…
What I do know is that I took a drastic measure and performed a full clean Windows and Game install and it solved EVERYTHING. I’m getting amazing performance in VR with super smooth frame rates (capped at 30). It’s a lot of work I know, but it’s nothing compared to the time we all invest in this game. It doesn’t forgive Asobo for letting this bug remain tho.