Are these really performance extensions? They look more like extensions to simplify the creation of common charts like geo, stacked bar graphs, etc.<p>edit: The library looks pretty slick though--I like the fluent interface for describing a chart, and how it doesn't try to hide the lower level D3 functions. Here's a an example I found on their github: <a href="https://github.com/alexandersimoes/d3plus/blob/master/examples/dataviva/stacked.html" rel="nofollow">https://github.com/alexandersimoes/d3plus/blob/master/exampl...</a>