I have the same GPU and CPU too and I get 70-90 FPS on ultra settings. When I enable Frame Generation it lowers my FPS. Could you help me? I only have problems with this game.
Specs:
B650m-Plus Wifi
Ryzen 7 7800x3d
Asus Tuf 4090 OC
Corsair 6000mhz 32GB
Kingston 2TB 7000mb/s SSD
Asus Rog Strix 850w Gold Aura
Hi @Komutan8021, welcome to the Microsoft Flight Simulator Forum!
The DevMode FPS Display shows your FPS (of actual frames) before Frame Generation doubles it. This is because the Frame Generation takes place outside of MSFS.
To get your actual FPS you can either double the figure shown in the FPS Display, or you can use an external FPS counter 
In your screenshot above you were actually getting 52.9x2=105.8FPS!
So actually my FPS levels are normal right?
For the in-sim FPS counter with Frame Generation switched on, yes.
Mine does exactly the same thing. I lose some FPS on that display, but Afterburner/Rivatuner reports double the amount shown in the sim. I go roughly from 55FPS down to 45, which is doubled to 90 by Frame Gen.
I just noticed something about Frame Generation or TAA that I believe got recently broken in MSFS (at least for me). When I enable FG with any type of AA except DLSS, my framerate absolutely crashes and the game is very Mainthread limited everywhere, like 25 fps. I have a 5800X3D and 4080, and normally on simple default airports I get 60 fps, doubled to 120 fps with FG. This used to work fine with TAA, which I prefer due to better clarify for glass cockpit font.
Recently I noticed that my framerates went way down, and I noticed that this happens when I have FG enabled with TAA. FG still works with TAA, but instead of my framerate being 60 x 2 = 120, it’s 25 x 2 = 50, the fps counter going red and purple. No matter how much I lower detail level, even medium only gets me like 30 fps in a small default airport. In busy scenery it becomes really jerky and unplayable.
If I replace TAA with DLSS, I’m back to a smooth 60 fps, happy green fps counter.
I noticed that with FG disabled, I get more fps with TAA, but it’s still not great, maybe 40 fps tops in a small airport. I tired older drivers, didn’t make a difference.
Hi. I see that many options has been tried and nothing helped. I have a similar issue with the same setup but 4080 instead, and what actually help was set Full Screen option but in NVIDIA Control Panel instead of game client. It cost nothing to try so I would propose to try it.
In NVIDIA Control Panel: