The web techradar.com chose SMPlayer as best performing media player for 2014.

The winner of our roundup was SMPlayer. It wasn't the quickest player to
launch and load files, but it never took more than two seconds, which we
think is an acceptable wait. It excelled where it mattered though - in
CPU and memory performance. Thanks to a maximum memory footprint of just
80MB, and average CPU utilisation just that little bit more efficient
than the other two players on the podium, SMPlayer emerges as the best
performing media player for 2014.

You can read the whole article here.

(Of course, the good performing is due to mplayer)