Depends on plane (I don’t like glass cockpits f.ex.) I fly mostly DC-6, Pipper Arrow. And I’m not saying about boring flying over New York 
I’m sure that since months I didn’t saw as low as 18 fps. It don’t go lower than 30 fps for me and no stutters. I’d have to check later, but I’m quite sure that I have 100/100 or 85(msfs)/120(openxr) (what results with still full res, but some upscaling on WMR side). Remember that CPU/GPU is not only thing matters - as I mentioned earlier - thermals, network connection, fast drive and so on matters. 
I will check and do some benchmark, probably not today, but I will try to remember and post results.