GPU vs CPU for Animation Resource Usage

I am creating a character for my game that I am worried if it is going to be heavy for gpu/cpu usage. This is my first game and I will do tests myself too but I thought it would be good to have a general understanding first. I am thinking of creating lower poly option to make it less resource intensive, but I am not sure about GPU/CPU usage percentage for animating skeletal meshes and how much it differs from rendering static meshes.

So I wonder animation if animation is CPU or GPU intensive for Unreal Engine. Are new vertex location calculations for animation made by CPU or GPU? If both are used which one is creates bottleneck for high poly animation? How will this situation change when Nanite will be capable of rendering skeletal meshes? Thanks.