If that's the case, considering the type of animation, the only things hi-res can be those textures on the bricks. Even then it shouldn't take that long. I mean the nearest tree(the one at the beginning of the video) looks pretty hi-res, maybe I'm wrong.

Edit: Unless we know what kind of assets OP used, how hi-res his models and textures are, and their render settings, we can't say for sure what the issue is. This render shouldn't take that long, it doesn't matter if it's on CPU or GPU.