Working for a site that has tens of millions pageviews a day and makes heavy use of CSS sprites, I'd like to share some "real-world" results. The bottom line IMHO is that we've had good performance gains using CSS sprites, mainly because of:
- Reduced http requests overhead
- Incremental TCP speed (one big file goes faster than many small
ones, because TCP speed increments over time)
This doesn't change much between broadband and narrowband connections, as far as we've observed. Using CSS sprites, you get also a snappier rendering of the page, because once the graphics file has been decompressed, it is instantly available all over the page.
Of course, the best results are achieved when the graphics file is preloaded (for example at login) and kept in the browsers' cache. That leads to another problem: you'll have to append a version number to the file name, to refresh your users' caches in case the graphics get updated. The version number can be a parameter like image.png?v=12345.
HTH
Cheers, Corrado Fiore _______________________________________________ List info: http://lists.roundcube.net/dev/