I found that on my system DX12 works in 2D/not VR mode, but is sensitive to mods. For example, loading into the asset heavy KRNT Drzewiecki Design Renton airport will always CTD in VR and take a long time to load in 2D. Other custom or stock airports are much quicker. If I fly out of, say KBOS, with the same plane it’ll work in VR or 2D with DX12, but in VR, it will eventually CTD a few minutes into the flight. No such problem with DX11. Performance seems good while it’s running. Sticking with DX11 for now.
One interesting note. With the custom KRNT, I can load into it in 2D, and then, if I load WMR (using HP G2) and go into VR while the plane is loaded and on the tarmac, I can avoid a CTD, but an error alert pops up and it crashes. I’ll try to capture that and update this post with it.