It runs a perfect 60 FPS on Chrome here and 23-24FPS landscape on an iPad 3 as 
Arima also found. It looks like it uses very large textures which is likely to cause poor performance on mobile. For example the red border and the stars in the background are both full screen size textures, which like Arima points out will cause full-screen overdraw twice when you could simply have had four small red objects around the edge and lots of individual small star objects placed across the layout. That would probably reduce your overdraw by 40% already for an easy optimisation.
I think it's unlikely this type of thing would even run well in a native engine. It's all hardware accelerated and drawing on the GPU so it probably wouldn't actually render faster in a native engine. Mobile devices just have *much* weaker hardware than desktops and you have to be careful not to throw too much at them.