When I worked for MLive.com, one of our practices was to leave out quotes around attribute values (except for alt attributes). This was to save on bandwidth costs. In spite of the fact that the page was no longer valid HTML (technically), all target browsers rendered the pages properly.
That might seem like nitpicking, but with over a million pageviews a day, all that ASCII can add up. Personally, I would prefer valid HTML, but I bet the financial side of that decision was pretty interesting.
I’d heard a rumor that, for similar reasons, Yahoo! used extremely short filenames for images, e.g. a.gif, b.gif, c.gif, etc. I don’t know if this was ever true, but it doesn’t appear to be now.
When I still relied heavily on transparent spacer GIFs, I put a 1×1 pixel transparent GIF at the server root (/1.gif) to achieve the shortest possible filename.
A few months ago, I noticed an interesting technique that Google uses to save bandwidth. Check out the logo image that they use on their search results page:
They can use the same background image several times on the same page by changing the background position via CSS. That means one image call for multiple images. One roundtrip from client to server, after which the image is cached and reused. The colors are similar between the images, so the file size is not substantially increased over the size of 3 separate images. This technique may not save Google a lot of bandwidth, but it speeds things up for the user and presumably reduces the load on Google’s servers.
Now I work on sites that don’t have a fraction of the traffic of a Google or even an MLive, and such bandwidth-saving techniques are largely unnecessary (from a costs standpoint) and ignored. But I still have a lot of respect for such clever ideas.
Now that more users are accessing the web from their phones, I think we could all stand to pay more attention to bandwidth again. I know that my phone cringes when it’s working on a 300K page (that in reality should be 30K). Maybe it’s time the 5K Contest was resurrected.