I come back to report the experience with 13 tMBP + UltraFind 5K combination:
First a simple photo
A great look, I don't care the thick edge that much.
This is my tMBP, 2.9GHz i5 + 16GB RAM + 256GB SSD + Iris 550 Graphic
Devices
- UltraFine 5K connected to MBP
- Bluetooth connected Magic Keyboard & Touchpad
- Bluetooth connected iPhone
- No other devices connected
- Light up both the 5K display and MBP's internal display
- On MBP I have 2560x1600 backgrounds around 1MB, on 5K display the background is 5120x2880 images about 1.5MB in size
The short answer
It's not a happy experience using this combination, I have returned the 13' MBP, ordering a 15' with 460 graphics instaed
Daily use
- Mission control animation is extremely laggy, after a few times it becomes smooth for a while
- Switching between desktops is also a little laggy
Chrome
Try to open
http://www.apple.com/, the animation on the homepage cannot run smoothly, FPS drops
Typing
Using the default input method on Sierra, daily input is smooth, however if a Chrome's active tab has some animation, the input experience is VERY VERY laggy - which I cannot bare
High CPU scenario
Try a ffmpeg to exhaust my CPU:
ffmpeg -i input.mkv -vcodec libx264 -acodec aac -crf 18 output.mp4
It runs at 2.1x speed and drain more than 90% of my CPU, I have identical experience in this time, everything formerly smooth is still smooth
Video play
Fail to play a 4K video so I didn't get it tested