@JayGeeTech, 13900K is definitely worth the upgrade from the 10900K with regard to MSFS. Annoyingly, most of the reviews compare it to the 12900K, where it’s only a bit faster, but going back three generations to the 10900K it’s a solid boost. I’d estimate I’m getting about 150% of the FPS on CPU-limited areas (without factoring in the 4090 doubling) on the 13900K vs. the 10900K. Which is the difference between 35-40 fps and 50-60 fps in the most demanding areas. It’s less of a factor if you get a 4000-series card, but because the base frame rate is higher it still feels noticeably smoother than it did on my 10900K.
Using a flight over NYC from KLGA with details cranked to 250 LOD, 200 object detail, here’s the average frame rate I was getting:
10900K, 3080 10GB: 40 fps
10900K, 4090: 72 fps
13900K, 4090: 98 fps
Also check out my post on performance with FSLTL running.