Jittery playback of mkv files

I am evaluating MiRow vs Plex. I have a main title mkv of Hairspray generated with MakeMKV (v1.6.2). It plays back flawlessly on Plex but chokes with MiRow. The audio is o.k. but video is blocky & choppy – unwatchable. I am using the latest versions of Plex (v0.9.1.2) and MiRow (v1.0.2) on a 2.8 iMac with 4Gb ram. Any ideas on how to fix this?

Sorry, we're working to improve support for higher profile HD files in an upcoming version.