The Matroska Media container is a very popular, open standard Multimedia container which is usually found as .MKV files. It is a very popular format in enthusiast circles and can be played directly in VLC or Windows Media Player with suitable codecs installed.
We played our 1080P MKV rip of The Dark Knight using the latest version of VLC Media Player.
CPU utilisation manages to decrease with an increased CPU frequency, although the 1% difference has little meaning, especially when numerical rounding is taking into account.