Is there anyone who can help me out with some feedback on graphics performance running a 4K display at 60Hz on OS X El Capitan? Most reviews on the OS, especially ars technica, claim that performance for 4k displays has dramatically improved. Unfortunately there is only very little detail on which hardware is concerned. From what I can sum up so far with 10.11 (15A284) only certain integrated Intel chipsets seem to profit from the newly introduced metal graphics engine. Discrete graphics should be integrated into Metal later on in future releases of OS X. Nonetheless users with discrete graphics (Mac Pro, nVidia 750M) are reporting better (graphics) performance with their setups on these forums. Back in june i have been testing numerous displays connected to a rMBP 13" 2015 on Yosemite. Unfortunately my impression was that the latest MacBook Pro is not capable of rendering a 4K desktop smoothly. Animations would stutter a lot - up to a level where to my liking the experience was not acceptable. Seems others would share my impressions, as one can find numerous posts and videos on youtube about UI lag - for example on the latest rMBP 13". I made up a short theory of how desktop performance would be affected back then: HiDPI Scaling mode (Best for Display>More Space) x Transparency Setting (Reduced transparency On>Off) x Clamshell mode (Lid closed<Lid opened) UI transition would be a lot better, when every factor would be set to positive (green), but even then the interface looked choppy and felt unresponsive at times. The displays I have been testing are the following: Dell UP2414Q (4K [UltraHD 3840x2160@60Hz] MST via rMBP 13" Early 2015) Samsung U32D970Q (4K [UltraHD 3840x2160@60Hz] SST via rMBP 13" Early 2015) Dell UP2715K (5K [5120x2880@60Hz] MST via iMac 5K Late 2014; 4K [UltraHD 3840x2160@60Hz] via rMBP 13" Early 2015,) I returned all of the products and settled with an iMac 5K afterwards. This one performed nicely running Yosemite and also works flawlessly on El Capitan. - Still I would prefer a mobile solution in case it was possible now. As I do not currently have the time to test for myself any feedback would be very much appreciated. Please also provide details on your monitor, HiDPI Scaling mode, Mac and - if it's a MacBook - whether you are running in clamshell mode.