Although you have already found an answer to your query, I would like to throw this out there for everyone, as I've found it pretty close to Godsent for watching streams while boxing:

There is a nifty little command line program called Livestreamer. It'll allow you to feed a stream straight to VLC/MPC/a few other players instead of using the ridiculously resource hogging default flash player on twitch. With a quick test it appears (for me atleast) to only require about 10% of the CPU power required for watching normally on Twitch.

You can either launch the stream through your command line manually, or for firefox users there is also an add-on that adds a right-click functionality for twitch to launch streams with it.