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Question: Why don't you use mod_deflate, mod_gzip, or other related compression?

As of November, 2007, we now use mod_deflate in Apache 2 installs and mod_gzip in Apache 1.3 installs by default. Since we wrote our previous FAQ entry CPU capacity has progressed enough to make the load increase negligible and the modules themselves have improved significantly to allow yes/no rules to be included to control what gets zipped up and what doesn't.

If you would like your site to NOT be gzipped by default, please let us know. We can turn it off on a per-virtualhost basis.


The following is left here for historical purposes only:

Three reasons:

1) Zipping everything before it goes out increases the load on the server. This is significant especially when the server is getting lots of hits.

2) Just about all you can safely zip is text, html, and xml, most of which is small already and/or is generated by scripting languages (PHP/PERL/JSP/etc) that have compression capabilities built in. Everything else (mp3, mpeg, wmv, jpg, gif, png, etc...) is already compressed and will actually be larger and slower if you try to zip them.

3) A zipped website has to be completely transferred before the browser can decompress it and render it. Uncompressed html on the other hand gets rendered by the browser as it is downloaded. Thus uncompressed html will often appear to download and display faster, even if the complete download takes a second or two longer.