[tga]

"With OS X Yosemite 10.10.3 and later, most SST 4K (3840 x 2160) displays are supported at 60Hz on these Mac computers:

    MacBook Air (Early 2015) and later
    MacBook Pro (Retina, 13-inch, Early 2015) and later
    MacBook Pro (Retina, 15-inch, Mid 2014) and later"

https://support.apple.com/en-us/HT206587

Earlier years will only do 30Hz, which is fully usable for development/office work.

[irq]

Anecdote: I find 30 Hz to be totally unusable for development/office work. The jerky movement of the mouse cursor, jerky scrolling, etc, is all painful to my eyes. So, I think very much, YMMV, but 60 Hz is safe.

[girvo]

Agreed, so much so that I gave up on 4K, scaled it to 1440p just to get 60hz on my (now-dead) 2013 rMBP with my external monitor.

Recently bought a second-hand perfect condition 2016 MBP with function-keys, and it's been brilliant so far, and I get proper 4K :)

[pier25]

Yeah me too. It feels like the mouse is lagging.

[photojosh]

Note the "SST 4K" criteria. I have a late 2013 15" MBP that drives 4K at 60 Hz, but it is an MST "multi-screen transport" display (which requires enabling on the monitor menu). Don't know if they're made anymore. Mine is a Dell UP2414Q.