Ok, so that’s your choice then. If you’re happy with sub-20 fps, that’s cool. But your use case is not the norm, and most people aren’t playing at sub-20 fps. If you can’t even tweak to ensure 17 fps, your PC is way underpowered for what you’re trying to do.
The larger point remains - your PC is under-powered for MSFS, and if you’re expecting PMDG planes to be smooth on this machine… you may be disappointed.