When my frames drop as much as 25-50% after two hours of flight time, my GPU usage is running 100%. It is really never lower creating those 50-60 FPS. CPU is consistently running between 25-30% usage. GPU temp never runs greater than 80 deg. C. As far as spikes, however, I really don’t have those, just a gradual drop in FPS until sim is unplayable. As I mentioned in a similar writeup, if I SAVE the flight when FPS is at its lowest, turn off the sim and then go back to the Saved flight, my FPS is back to 50-60!