Default Stuttering during video playback

I often watch a movie or TV serie on my phone before sleeping, but I have noticed that the video payback is not always smooth and there are slight stutters as if the G3 doesn't have enough power to play back full HD high bitrate, particularly in Matroska formats. So whats up with this? I know the G3 is plenty powerful to be able to play without stutter, so could it be some kind of power saving feature holding the cpu performance back and causing stuttering? This is ridiculous to be happening with a flag ship phone! Any ideas on how to fix this?