I must have missed the Data URI hype, because I'm not at all shocked that CSS spriting is faster than using Data URI. We are comparing using a binary image for

I must have missed the Data URI hype, because I'm not at all shocked that CSS spriting is faster than using Data URI. We are comparing using a binary image format, and a base64 encoded image inlined into CSS/HTML. What isthe basis or the source of the idea that base64 encoded images inlined into the CSS would be faster?