In April 2010, Google made an announcement that they were including web page loading speed as a metric for page rank. This reiterates the importance of having strong technical skills to hand in achieving SEO. At the same time, Google offered a number of tools to help webmasters achieve faster page loading times.
One of these tools is a browser plugin for Firefox/Firebug, once installed you access the information from the Firebug console. Page Speed rates elements of your page, how quickly it loads and offers advice on how to speed it up. This includes tips such as minifying JS and CSS, serving static content from cookieless domains, putting JS and CSS in the right order in your pages and so on and hundreds of other rules. There have been other such plugins available before, such as Yahoo’s YSlow which does much the same although both can be used in conjunction with each other as they cover slightly different rule sets.
The other ‘tool’ that Google offer is an Apache module, mod_pagespeed, that actually does a lot of rewriting on the way out. The module works only for Apache 2.2+ and can be configured to make a lot of the changes that are recommended by the plugin. For example, it can strip whitespace out of files it serves, minifies JS and CSS, can reduce images, serve images as inline data:// and do all manner of other things.
Installing mod_pagespeed on Debian or Ubuntu proves pretty straightforward. The steps, as root on a 32 bit system, are:-
dpkg -i mod-pagespeed*.deb
apt-get -f install
Once installed, you can configure the module:-
By default, very little change is made to your serving environment but you can add in ‘filters’ to the config file. For example, to have the server combine all CSS files into a single file, add the filter:
To minify CSS, add this filter:-
After installation and any configuration changes you must restart Apache and straight away you will see the results, with pages being rewritten on the fly to reduce the amount of data being transferred and the number of round trips to the server. Familiarise yourself with the different filters available for mod_pagespeed and make sure that you configure the module in the way that you wish. Be aware that each module carries an element of risk which is outlined in the documentation. For example, some of the page rewriting may break your pages if you walk the DOM using an expected structure rather than dynamically. Risks associated with each filter are clearly outlined and you must decide whether each is likely to cause problems on your site.
mod_pagespeed is still only in Beta, it was only launched in November 2010 so this is still early days, but our experience with this module shows that it is a good weapon to add to the SEO arsenal, provided you are running Apache 2.2, and webmasters should welcome it, particularly in environments where there are many developers contributing to web content, some of whom may not have much of an insight into optimising pages.