By Jeff Kaufman, Software Engineer, PageSpeed Team
Making your site fast shouldn’t require lots of manual optimization. With mod_pagespeed, an open-source Apache module, you can automatically apply web performance optimization best practices like cache extension, image optimization, and css inlining to speed up your site without a lot of hassle. As of version 0.10.22.4, mod_pagespeed now supports A/B tests integrated with Google Analytics, allowing you to measure how much it speeds up your site on live traffic and experimentally determine the best settings.
We ran an example experiment, comparing mod_pagespeed running with default settings to mod_pagespeed in pass-through mode, on a small blog. This required adding the following lines to our
ModPagespeedRunExperiment on ModPagespeedAnalyticsID "UA-XXXXXXXX-Y" # half the users get the pagespeed optimizations ModPagespeedExperimentSpec id=3;percent=50;default # half get an unoptimized site ModPagespeedExperimentSpec id=4;percent=50