Note: This is a guest post from Ismail Elshareef, who is the Principal Architect at Edmunds.com. Thanks for the post and for making the web faster Ismail!

In the Fall of 2008, we embarked on a complete redesign of our car enthusiast site, insideline.com. One of the main redesign objectives was to deliver the fastest page load possible to our consumers. Leading up to that point, we have been closely following and implementing the performance best practices championed by Google’s Make the Web Faster team and others. We understood the impact performance has on user experience and the bottom line.

Some of the many performance-enhancing features that have been implemented on insideline.com (and now on our beta.edmunds.com) are:

1. Reducing the number of HTTP requests: We combined CSS and JavaScript files as necessary as well as using sprites and data URIs when appropriate. We have also reduced the number of blocking requests as much as possible to make the pages “feel” faster
2. Serving static content from different domains: This helped maximize the browser parallel download capacity and made the request payload faster since no cookies were sent over the wire to those domains
3. Using Expires headers: Caching static files in the client’s browser to eliminate unnecessary, redundant requests to our servers
4. Lazy-loading Page Modules: Render the bare minimum page components first so that the user sees something on the page, and then go through the modules and load them in order of priority. We developed a JavaScript Loader component to help us accomplish that which you can read more on the Edmunds technology blog.
5. Managing 3rd-party components: iFrame components could be lazy-loaded without a problem. JavaScript components, on the other hand, need to be loaded onto the page before the onLoad event fires. That had the potential of slowing down our pages. The solution we devised was to delay the calling of those components until we initiate the lazy-loading of modules and right before the onLoad event fires
6. Using non-blocking calls: With the browser being a single thread process, we optimized ways of including resources on the page without affecting page rendering so that the page is perceived to be fast by the user.

The results on insideline.com have been incredbile. Page load time went from 9 seconds on average on the old site to 1.5 seconds on average on the new one, and that’s with loading in much richer content onto the page (measured with WebPageTest). We have also seen a 3% increase in ad revenue. On the beta.edmunds.com, which will replace our legacy site fully in December 2010, we have seen a 17% increase in page views and a 2% reduction in the bounce rate for our landing pages in a controlled experiment.

Although we have a long way to go in making our pages and services faster, we are very pleased of the progress we’ve made so far. Working with Google to make the web faster has been an exciting adventure that will continue with more improvements and innovations for both our sites and the web as a whole. Get more details on the Edmunds technology blog and try these enhancements on your site today.

By Ismail Elshareef, Principal Architect, Edmunds.com