You don’t say what resolution you are using but if it’s 4K then turn it down to 1440p (use windowed) set the GFX to Medium and turn off rolling cache, then fly fast and low in the XCub. This should let you know if it’s the game or something else that’s struggling and then you can work up from there. Your gear should let you run 40+ and smooth with High End GFX although I would recommend having FS2020 on a separate SSD.