For me, the frame rate hit happens the second an instrument of some kind is popped out, like a PFD, MFD, etc. Doesn’t matter if it’s sitting on the same monitor or moved to one of my other monitors. The act of breaking out the instrument is what causes that performance hit. That has nothing to do with multi-monitor support. That has everything to do with inefficient re-rendering of the instruments in the new “container” it creates vs mirroring the original.
I have 3 monitors hard-wired to my system normally (2 atm - did some desk rearranging and waiting for another VESA arm to arrive). My main is a 34" 3440 x 1440, on the right I have a 27" 4K, on the left an old 1200p 24". The game only runs on my centre 34" monitor. But I can move the popped out instruments to any monitor, and that has no impact on performance at all.
And I also have 2 tablets connected over Wi-Fi using SpaceDesk. Again, I take the frame rate hit breaking out the instrument, but I can move it to either tablet without any additional performance loss.
In the case of my screen shot in my OP, I was running SpaceDesk on my old phone, and moved the TBM’s touch screen to that. Again, no performance decrease from doing that. THe performance hit came from breaking it out.
But back to the main issue - touch screen support is only supported in the virtual cockpit itself, and not on the popped out instrument windows. It registers the touch as a mouse click, but not the position. The mouse click will be sent to whatever position your cursor is on your main screen in the v-cockpit instead of that you actually are tapping on. Even if it’s on the same monitor.
If you’re using SpaceDesk or something of the link on your Surface tablet, make sure it’s not set to use the default low frame rate. That could explain that rotten performance you’re seeing.It did it to me until I realized you could adjust frame rate in the client software