Wow. How the hell do you (OP) get it to render so fast? That was instantaneous as far as I could tell. I've seen websites take 5x as long to add a <li> to a <ul> ... I'm really amazed.
Heh, your browser does most of the hard stuff :)
I'm not quite sure what others are doing that it's slow.
I'm stunned. I was expecting it to chug with something like that, but nope, instant.
You're not kidding; it is virtually instantaneous in Chrome, IE9 & Firefox.
Even on my AMD E-450 netbook, that was pretty much instant. Lagged a lot afterwards (to be expected, running FF on elementary Luna), but way better than I thought it would! Well done OP, seriously well done.
Perhaps it has something to do with using SVG rather than just HTML elements?