In regard to different readings, it is likely that MSI Afterburner is reading the FPS of the internal FPS counter, not actually the game.
OK, in regard to your primary concern, I do have 3700x + 2060S and I run it at 2560 x 1080. I got similar but a bit better FPS here. A few things I noticed that could improve the FPS in the cockpit are
- CPU Frequency/Memory Frequency
- 2D Instrument Panel Tweak (lower refresh rate in the JSON file). This helped other people gain 5 - 10fps Small JS config file mod to gain 10/15+ FPS in airliners and glass cockpit planes
Btw, you can totally turn up you graphics settings (I changed my rendering scaling to 150%) because this is a CPU limited scenario
