Are they relevant to this implementation?

What I mean is this is a client-side javascript library, so it is meant to work in the browser on who knows how powerful hardware.

There may be facial recognition libraries that work very well in real time, but how powerful of hardware is required?

And the other big question, are they proprietary algorithms or open-source?

That's really good to hear! The face tracker was one of the first modules to be implemented on tracking.js and, back then, we found Viola-Jones to be the most promising algorithm to make face detection (besides being the one used by our main reference, OpenCV). The whole library was refactored for this release, but we didn't change the algorithm and perhaps it is already out of date. We would be grateful if you could help us by sending papers about better algorithms (and reference implementations?).