Performance improvement according to CPU

I know that the amd Ryzen X3D model has good single core performance.
Rhino is also a program that mainly uses a single core, so if I use the x3d model, is it faster than the non-x3d model?

Ryzen X3D will make next to no difference for Rhino performance. It is a 3D V-Cache that allows fast L3 texture access for the CPU cores, with massive capacity. Hence, it mostly trounces AMD X equivalents and nearly all Intel CPUs in gaming scenarios, where it increases your FPS. You may notionally see a difference in things like TestMaxSpeed, rendered viewport or something. But in 99.9% of instances in Rhino, it won’t matter at all, especially as the FPS tends to be already very high in viewport.

For productivity in general, all things become basically equal again with sometimes the X variant performing better than the equivalent X3D part in production software. Recent driver updates may have changed that.