Ever since we started FastMail, we've been using server side compression to compress and serve HTML pages, first with mod_accel and more recently nginx. Using this significantly improves the download speed of HTML pages and makes the site significantly faster for end users.

However for a long time we haven't compressed javascript or stylesheet (css) data. The main reason for this has been bugs over the years that have made this unreliable, most notably these bugs and others in Internet Explorer.



Since more and more sites are now compressing these files, and IE6 is being replaced rapidly by IE7 and Firefox, I've decided that it's time again to turn on compression for these files and see how they fare. I'll update this post if there's significant problems and I have to turn it off, but hopefully we can now leave this on as a standard feature, saving a bit more time on page loading.