Choppy playaback issues with large MKV files (17gb+)?

Does anyone have problems playing back large MKV files? I was watching Star Wars: RotJ and the playback slows down and becomes choppy every 10 seconds or so. It doesn't buffer, it just get choppy.

My AFTV plays small and medium size (8-14gb) MKV files just fine.

Is there any way to fix this?