Hi. For the people with a 13" 2015 MacBook Pro with an external 4K display, I want to ask if the integrated Iris 6100 graphics can move easily an external display with such resolution @ 60Hz with no lags. I mean, a fluid experience with Mission Control, and full screen apps, as well as streaming content (not necessarily in 4K) And the people with the 2017 nTB MacBook Pro with an external 4K display, connected via thunderbolt 3.0 (USB-C), how is the performance? If I plan to purchase a 4K monitor in the next few months/years, is it worth the investment in a new 2017 13" nTB MacBook Pro? Or I will be OK with the 2015 13" rMBP? I'm asking this because I've read that the graphic power of the integrated graphics card is not much higher on newer MacBook pros... Although they have the eDRAM caché. Thank you!