Personally, I turn the screen off because my monitor is an OLED, so it is more as a precaution. But the answer to your question is still that it doesn’t matter if you have a 4k monitor or a 1080p monitor, it isn’t going to make a difference to your G2 VR performance. The VR mirror that is displayed on your PC monitor while you are gaming in VR is a negligible performance hit and is not the reason you are bottenecking in VR. Especially in MSFS, which is a nightmare overall for VR headsets at high resolutions.