Possibly-OFF-TOPIC-here
I see that ImageMagick can combine images in a single one.
A single image mean a single hit to a Apache, so it only have to spawn once.
On the clientside, a single image can draw multiple elements with some ninja CSS stuff. ( background-position?).
For such thing to be possible to a MediaWiki skins, do changes are needed?.
This is "minimize" but for graphics.
Is possible a idea for the future, for a future full of divs and CSS3 happynes.