Testing the technique laid out at http://peterhrynkow.com/how-to-compress-a-png-like-a-jpeg/ with external and inline assets. http://codepen.io/shshaw/pen/tKpdl/
Great technique! I have problem with Safari (both Win and Mac) since, as reported, external SVG with data-uri is not working BUT if I open SVG in separate tab Safari displays it normaly and then it's visible on main page also. And first example in this pen is also working across all browsers. Since seems that browser is capable displaying image, it's definetly some weird bug. It would be cool to figure some way around it.
Need to know how to enable it? Go here.