The same thing happened to me last night during my first flight, and at multiple instances during set-up and taxi as well. OTHH typically performs quite well for me, so I don't think it's the scenery, especially because it continued in cruise. I also experienced overspeeding on the climbout, and the aircraft ignored all speed constraints from the SID despite being present in the flight plan page.
I have a similarly specced system: 7950X3D and a 4090. MSFS 2020.