sp3 i7 4k files and also dts (choppy playback)

How do 4k files play back for you guys? youtube is fine but if I try to play files with less compression like the ones at 4ksamples.com they are so choppy as to be unplayable. I also find my sp can't handle any mkv files with dts audo, I have to downconvert them to play them.

If anyone has any tips on how it might be possible to get them to play smoothly I'd love to hear from you

Thanks

i'm guessing no one can play these files and its just beyond the capabilities of the sp3 then?