Faster light and shaders build

To increase speed of light and shader build do I need to use more powerful CPU or GPU ? I have now i5 4670K CPU and GTX 1060 GPU and 32GB RAM

In case of any code (Shader is code) processing it is done only on CPU, and compilation is one of those things that scales infinitely with number of cores, until you got more code files then cores, so more cores = better. Lightning can be done on both, but no sure which UE4 method use

so I think I better upgrade to AMD Ryzen for more cores.