Seems there is a bug in P3D V2 that causes FPS drop when using multiple windows. FPS starts from 25-30 in heavy scenery like in EFHK but eventually drops to 4-7 and it causes instability in our home cockpit environment. If you go to desktop and back to P3D then FPS goes back up and either stays there or then drops again.
Bug is confirmed by developers so we are waiting for next update. Until that only one window used, anyway it will give us 135 degree visual in sim. But of course in our 3 projector 180 degree visual it’s not good on edges.