[jol]

ok, but the article says that there is more images (btw, other media too), i.e. images make 50% of web page now and image size growth contibutes ~400KB out of ~900KB, images tend to change, given that top 1000 pages are dynamic, thus, no cache will help. Also I find it interesting that stylesheets are growing, given that css3 are more powerful now and IE6 is likely to be retired for most of these sites. What is interesting is what makes this "other" part? is it just webfonts or some media (also very cross-site cache friendly)?

[onion2k]

Image size could include things for retina displays, higher standard resolutions, CSS sprites and so on. Again though, a lot of images in sites are standard reusable assets that are held in the browser cache between visits - it's just editorial and user-contributed content that won't get much benefit from a well configured http server.

Sidenote: I found out about kraken.io on HN a while ago. I use it for all my images now. Usually gets at least 5% reduction on a well created picture, and 50%+ on a bad one. (No affiliate, just like it)

[jol]

I don't think that CSS sprites should be bigger, given that css is improving, I don't know about the sample analysed, but usually the editorial and user-contributed content images (as well as ads) take much more bandwidth than style related images, unless the site has exotic design. aside: kranken.io is nice