Website visitors have a low attention span. We’ve mentioned many times how crucial it is not to let page load times exceed 2-3 seconds. This was demonstrated by a test done at Amazon which showed that every 100ms increase in load time resulted in a 1% drop in sales. With Amazon’s annual turnover close to $50B, that would result in lost sales of $5B if the site took just 1 second longer to load.
After doing some research on Joomla and WordPress performance we found several performance tips for decreasing that load time. One of the important ones is to use server side caching. Fortunately, both applications have caching modules available.
For Joomla we installed a System Cache plugin that comes with Joomla. Details are at http://www.theartofjoomla.com/joomla-caching-explained.html. With the plugin installed, we saw a nice decrease of about 100 ms in response time, shortly after 12:00.
On WordPress we used a plugin called WP Super Cache: http://wordpress.org/extend/plugins/wp-super-cache/ and after installing it we achieved a noticeable drop in response time for our blog. You can see a ~90% drop at 16:00:
This shows how dramatic load time improvements can be when you use server side caching. If you plan on trying it out, the best way to measure the improvement is with our External and Fullpage monitors.