I recently upgraded to a state of the art system (7800 X3D, 64 MB DDR5, fast SSD, NVidia 4700).
When I use the sim I get around 40 FPS on a medium sized airport with traffic on - in a PMDG 737-900. The thing is - when I activate DLSS3 - the frames stay the same.
Have you enabled Game mode and HAGS in windows and restart your computer?
Search on YouTube how to set up your 7800X3D correctly in Windows + Frame Generation. Here is one that I used https://www.youtube.com/watch?v=4fhxlz6XCQE
Dev Mode FPS counter will show the true FPS and other FPS counters like Nvidia, game bar, afterburner will show the frame gen FPS which should be double like in this pic:-