I think this may be a bit too many instructions (I did not see hardware accelerated memcpy/memset though). I guess I would use only a small subset of them. Since RISC-V is a royalty free standard, writting directly assembly is worth it, until the abuse of a macro processor and code generation is avoided.

I want to share you optimism, but I advise you to keep your cool. There is a long road to reach the performance of x86/arm microarchitectures (it is harder for risc-v since the "market is over saturated"). And those performant implementations must get access to the best silicium node process... and that...