Hey there, I had this exact same problem and could not figure out why my performance would TANK when everyone else in the community would say pop out panels barely impacted their performance. It shouldn’t really matter how many you do, I can pop 1 or 5 instrument panels and mine seems to have about the same 3-4 FPS hit total, so not bad at all.
The solution that worked for me: doing a clean install of my nvidia GPU driver. I tried every other tip and trick I read and that people would give me, nothing worked. Finally just got fed up with it and did a CLEAN install of the nvidia driver (it’ll reset any custom settings you have, but if it fixes your FPS problem it’s worth it). After the install, went back in, started popping out panels and boom…only about a 3-4 FPS hit not matter how many I popped out.
I wish I had a more concrete answer for you, but honestly that is what worked for me, so just thought I’d share. Good luck!
***Disclaimer: I should mention I did this using the Citation Longitude, so I can’t speak for any other planes/instruments other than that, but I would assume if they’re default Asobo planes it should be similar results.