I’ve been happily using Rhino 5 on a 4K monitor for so long I don’t remember what all I did to set it up. I do remember it wasn’t satisfactory “out-of-the-box”. It also took a little while to get accustomed to the small size of the largest available icons. but it works fine for me now. Maybe I’m not normally as speedy on the mouse as you are. Come to think of it, I think I had to adjust the mouse dynamics to suit the new situation.