Hi,
I'm working on optimizing MediaWiki for front-end performance and came across a problem that seems to be an issue even on Wikipedia - images all get requested from the server for the subsequent requests even though all of them didn't change - this means that images that are cached in a browser are re-requested again. The problem is that even though all those requests return 304s and none of the images are actually transmitted, it still makes all those requests which delays rendering of the page.
I've wrote a patch and created a bug for this in Bugzilla: https://bugzilla.wikimedia.org/show_bug.cgi?id=17577
Let me know what you think.
Thank you,
Sergey