I'm new to graphics and all of that so forgive my lack of articulate info.  I have an MSI B350, Ryzen 5, 16G Ram, and just moved from a GTX 1060 to 1080 Superclocked.   I've done literally nothing between cards in relation to X-Plane and display settings, and could not get above 30 frames, and would run typically in about 23FPS.  No performance tweaking worked.  I thought I could max everything out with the 1080, I've heard stories and watched youtube til I'm blue in the face.  Finally I changed my GeForce control panel to "Let the 3D app decide", and changed my X-Plane graphics to Visual Effects 3/4, Texture and Antialiasing full, World objects full, no Reflection, no shadows, no parked aircraft, no Vsync.  That's a solid 45FPS standard screen, and 30 in VR.  If I pull Visual Effects back, FPS increases each time.  I've been able to get 98FPS just from those settings outside of VR, but I love the 30FPS VR and 45 Standard setup.  Looks great.  By the way, if I set Visual Effects to full, my 1080 chokes.  It's goofy.  My other resources don't even break a sweat and my 1080 sets at about 45% utilization on these settings.
I hope that helps.