That's not a library, that's a demo and it takes several seconds to load, just like a flash applet would.

I'm aware of minimalist things that can put stuff on-screen instantly, but not of something that's a fleshed out solution like SVG or Canvas that still loads instantly (like SVG or Canvas).

Edit: I'm sorry, my brain was still in 2d/Canvas/SVG/Flash land, you were talking about 3D stuff all along. You're right threejs stuff can load quickly, shaders can become a bottleneck though. I was thinking of a library that basically does "Flash Lite" with good performance and yet remains competitive with Canvas/SVG content in terms of load time. I'm not aware of such a solution, but I'd be glad to learn whether it now exists.

The haxe ecosystem is pretty great.

http://haxeflixel.com/demos/