first: i know, there's already a bug report. BUT: Its on 1.7.9 and closed, so i cannot post there. The reporter did not provide further information.

So, to answer the questions asked there:
Yes! It is still in every release-version of Minecraft. As soon as a UHD / 4k Screen is used, the View starts jumping around like crazy, playing is impossible. Also, if you try to type something, sometimes, chatbox (and text) shows up very late (from less than a second up to like 10 or more seconds).

The problem shows up every time, no matter if i have the 4k / UHD screen as main, second or even mirrored screen or if its operating without another screen.

For further information look there:

https://bugs.mojang.com/browse/MC-56707?jql=text%20~%20%224k%20monitor%22

http://www.minecraftforum.net/forums/support/unmodified-minecraft-client/2288248-minecraft-18-1-mouse-issue-on-4k-uhd-monitor