Why is the playback of musicvideos played not liquid?

All videos stutter during playback, whether SD or HD! … & I have the iMac 5K current generation!

Works perfectly on my system.


What are your specs… I still get stuttering…

Are there any settings you’ve adjusted?

What videoformat do play? mkv, avi, mp4…? SD or HD? External screen? Other specs & setting?

Is there anyone else where video playback works fine?