This problem persists and I don’t know where to go next. There are some suggestions that I have found in my search which might help but that I am not comfortable to attempt, like updating BIOS and updating chipset drivers. A fair bit beyond my skill set. What I have done is ensured that Windows is bang up to date and changed window Power Setting to High Performance ( I did try High Performance Optimized for Ryzen PCU and it got worse). I have also increased the Rolling Cache to 32Gig, although I have deliberately been repeatedly flying the same low density scenery route. I have just 2 aircraft in the community folder; removing them and flying default aircraft seems to make no difference.
One thing that I have noticed is that if I fly the route in the Got Gravel Savage Cub I don’t have the problem but if I do it in the BLL Cubcrafters X Cub (with Working Title G3X mod removed) then I do. GPU and CPU metrics don’t change between aircraft and they are all within limits.
Again, if anyone can offer a pointer to an old guy who isn’t on point with computer wizardry I will be grateful.