@Guest: There is no need explain why 30 doesn't divide into 144. Just divide. 4.8 is not a whole number. Perfect playability requres perfect divisibility. But because 144 is so much greater than 30 there will be no visible judder. First frame of the 30p video will make 5 frames at 144 Hz; 2nd frame will make 5; 3rd frame will make 5; 4th frame will make 5; 5th frame will make just 4; etc. Six times per second, ~35 milliseconds slips to ~28 milliseconds. I don't think this little hiccup is noticeable. It is much, much less of a judder than people do notice when playing 24p, 25p, 48p, and 50p videos at 60 Hz.
For your analysis of processing bottlenecks, the 5;5;5;5;4 cadence takes rather little work, hopefully by the video card, not the video player.