I'm a graphic designer and use apps like Sketch, Photoshop, Illustrator, etc. I notice when I'm working on complex files, my 4k display has noticeable refresh issues as the GPU is constantly playing catch up with what I'm doing. I'm connecting directly via DisplayPort @ 60hz. Normal computer usage is fine (web browsing, videos, document editing, etc). I've been using a 2015 rMBP (2.5 GHz i7, Radeon R9 M370Z 2GB GPU) and had to switch to a 2k display since it was affecting my work too much. So, I went ahead and bought a brand new maxed out 2017 rMBP (3.1 GHz i7, Radeon Pro 560 4GB GPU) hoping the newer chips would be much better. It's slightly better, but definitely not $3,000 better. Running the display at native 2160p or 1080p works fine on both machines. But the former makes the UI unusably small and the latter doesn't give me enough screen space. So– is MacBook hardware just not powerful enough to scale a 4k display at 1440p without a noticeable performance hit? Or could it possibly be my display (LG 27UD69)? I've tried multiple cables to rule that possible issue out.