HD Video in Chrome Browser is not working properly

I have an Android device with Android 4.2. It's a Box with an HDMI Output, to plug in to a TV. This box is capable of playing 1080p HD-Videos in the media-player app. However when I try to display a 720p Video (downscaled via ffmpeg) in the chrome or chromium browser, the framerate gets horribly low. (It varies between 15fps and 22fps) You can't really enjoy the video... When the video is not fullscreen, but in a smaller div-container it gets even worse! In the chrome://inspect-settings I have set the flags: - \#ignore-cpu-blacklist - \#show-fps-counter - \#enable-gpu-rasterization (force enable) When I do not set those flags, the video does not play at all. On the video-screenshot in the top right corner you can see, that the browser almost takes none of the available GPU-memory! Why is that? Can I do something about it? When I enter chrome://gpu it shows, that Hardware acceleration is supported. Nevertheless the output is just terrible... Do you have any tips how to improve HD-video playback in the browser? Best regards