Earlier quoted context omitted.
Similarly, I've never understood the purpose of ChromeCast. The lag makes it completely unusable for video (I'm getting ~1 frame / 3 seconds), making it a glorified radio with cellphone/laptop remotes.
Odd, I've streamed Netflix to Chromecast and my laptop video to Chromecast just fine. It may be your wifi connection.
Netflix is fast obviously because you are just telling the chromecast to stream netflix itself, not "casting" it to chromecast. Same goes with youtube.
However "casting" performance for me is even worse than the described .3fps on my Chromebook Pixel that isn't running ChromeOS. And my LAN is fast enough to use mplayer over ssh/x-forwarding... Trying chrome tab casting in Debian on a Chromebook Pixel burns the Pixel up, with it being very obvious that the Pixel is the bottleneck.
Trying to video encode the "cast" tab without using hardware support maybe? I'm not sure, I haven't really investigated it further.