About shaders… i was too experiencing slow shaders compilation time, usually i waited about 15-20 second to apply one node for preview. And i found information that, UEShaderWorker processes have low priority, and if you change priority for them, eventually they will comeback to low priority again, because its coded inside engine.
So, i found little software to control priority of shaders:
https://forums.unrealengine.com/community/community-content-tools-and-tutorials/1600540-ue4-shader-compiler-accelerator-for-win