My experience mirrors yours. I have a high-end Mac laptop, 16 gigs of memory, 1 TB SSD drive. Unreal Engine runs like total garbage on it. Moving around in a simple scene is incredibly slow and painful. Their keyboard controls are also pretty confusing and awful. I'd really like them to support something like the 3Dconnexion mouse[1], which would at least make moving around intuitive and easy, but it doesn't.[2]