Balls & Walls
http://labs.w-ll.org/js-balls/balls-and-walls.html
http://labs.w-ll.org/js-balls/faces.html
*I also made a version of faces.html with a unicode smiley “☻” to test performance against the smiley.png but atlas the major hog is CSS rotation. In the plain balls-and-walls.html demo we only move the element around the screen, and can completely ignore rotation due to the solid colors of the balls.