Hardware (CPU) advice - AMD 1950X and Rhino / Grasshopper

IPC performance has improved greatly with the ZEN architecture. About 40% better compared to their previous architecture, but not quite as good as intels current generation. though I doubt you would FEEL a difference. this is more something you would notice in benchmarks. IPC performance of Ryzen is certainly better compared to your current Core i7 920.

also read what I wrote about the X399 platform over here.

EDIT:
Here are some rendering Benchmarks: