My 2 cents:
IMHO the 3D Vcache on 5800X3D would provide a significant, generational jump in performance.
I would not make the upgrade with the expectation of super high FPS (useless on this sim anyhow).
However it should definitely address the smoothness/stutters issues you’re describing imho.
I recently spec’d such an upgrade in Europe, was around 320 for the CPU, another 230 for a fairly advanced MB, the Asrock x570 Phantom Gaming Velocita . Total 550.
Selling you current CPU/MB could offset this, for a net out of pocket cost of around 200/250. Picking up a B550 board could reduce the cost by another 100 Euros or so.
I think at that price the improved smoothness is more than worth it.
It would make the sim more comfortable and pleasing to use.
If you decide to go that route, your 3060ti VRAM will limit the resolution (no 4K ultra, 1080p Ultra yes, 1440p Ultra not sure, maybe).
The next most cost effective step: Upgrading the GPU for more VRAM and thus higher resolutions would set you back another 150 euros (e.g. the 16gb RX6800 can be had at 500 Euros brand new, your card could be sold around 350 on the used market).
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AFAIK @TotalMoon980154 has upgraded from 10700K to 5800X3D and has reported he is very satisfied . You can look up his comments history on this subject.
Maybe he could chime in and advise further.
However his GPU is different from yours (he has a RX 6800).