Sure - also on your computer from 2000 the fans would be on all the time time, one fan would have a bad bearing, and the HD would literally be making a crunching sound, and you would constantly be cleaning gunk off the mouse ball.

I can absolutely make a native version that's considerably less efficient than this one.

And yes, a more efficient browser version is possible (and possibly simpler). People like to fixate on platforms, but it's all about implementation.