As the animation loops it uses the same set of images over again. But as they all have a Cache-Control header with a value of "public, max-age=0, must-revalidat

As the animation loops it uses the same set of images over again. But as they all have a Cache-Control header with a value of "public, max-age=0, must-revalidate" the browser makes another request for every one of the images, every loop of the animation. It results in transfer of something of the order of 0.6MB/sec, with no end.