Just out of interest since I don’t play in flatscreen anymore I thought it would be interesting to see how my performance compares in 2D to give you something to weigh up against as we are not miles apart in specs.
By way of comparison, I loaded up the FBW A320 ready to go on the runway at Orlando (KMCO) and waited for everything to start up and settle down.
Settings at 4K, 100% render resolution and the standard “Ultra” graphics preset (note this appears to set displays refresh rate to medium) with broken clouds.
FBW got 32fps sat on the ground, limited by GPU. Mainthread not limiting but running at about 22-23ms
Stock 320 got 34fps limited by GPU. This time mainthread is marginally better at around 21-22ms, so for me there is a very slight performance penalty to the FBW on the ground.
Repeated the experiment in the air, again all same settings but choosing Kennedy space centre as the start point, Orlando as destination. I climbed up to 10,000ft and checked performance by just observing for a couple of minutes flying.
FBW got 41 minimum to 57 maximum flickering constantly between mainthread and GPU limited. Mainthread bouncing around too much to read reliably but generally 13-16ms I would say.
Stock got 53 minimum to 63fps maximum and was still flickering between Mainthread and GPU limited but spent much more time in GPU limited. Mainthread seemed to be significantly more stable and easier to read at around 12-13ms.
My specs are 3090FE with a small undervolt @ 1980mhz in game, 5800X @ 4750mhz, 32gb @ 3600mhz CL16 so should be broadly comparable to yours if you wanted to reproduce the test conditions and see how they compare. The FBW defo more performance hungry in flight, but it’s much much better so worth the trade off personally!
edit - oh and worth noting that last month Seb mentioned specifically that the displays have been moved off to their own thread in the DX12 update, so the displays sucking so much perf should be improved substantially.