Some additional things a long those lines I have done to score some more FPS:
- Turn off the VFR map: In the mouseover toolbar at the top of the screen, click the custom toolbar button (a cog) and disable VFR map.
- Enable generic planes for both both the AI and Players in the graphics options.
- My first flight when just opening MSFS is my best performing flight, FPS seems to decrease each additional flight until I close and re-open MSFS.