Regarding the topic “optimizing page-loading-times” too many people still set the focus only on the server-side, ignoring the fact that most of the loading time is spent getting all the components of the page(CSS, JavaScript, images, ads).
The

yahoo performance-team proved this very well.

Also, pages (like tilllate.com) more often make heavy use of JavaScript with the goal of providing a better user experience. The problem is, that most developers work on modern hardware and develop on their favourite web browser – which is usually a recent one. They forget that a big amount of visitors still

surf with their first computer bought 7 years ago at Interdiscount and is mostly surfing on the developers least favourite browser (like IE 6). As a result, those visitors often do not get the optimal user-experience and the website loses traffic (=money).

The conclusion out of this is:

• We have to optimize our page following yahoo’s findings.


• We have to optimize our JavaScript-execution.

Where to start?

Most of our traffic is generated through the photo album. We analyzed and improved following use-case in terms of loading-speed and responsiveness:

User comes to homepage…

…goes to the a photoalbum…

…clicks through the photos

Tweaks

We then did the following things:

• Reduced HTTP requests needed to load the JavaScript files: from 45 to 1-2 requests by merging the multiple files into a single one.


• reduced file sizes of CSS- and JavaScript files by using yui-compressor


• reduced amount of external scripts (like Google Analytics) or load them after everything else to reduce the dependency on third party hosts

Also with the photo album being a JavaScript app we went through the code and implemented the following improvements:

• reduced DOM-operations


• reduced amount of written code by refactoring


• found and removed some common memory leak-patterns


• removed fancy fading-effects as they were useless and took a lot of CPU time

The results

For example on IE7

(50% of our users are using it) we had following improvements:

• time loading and set up the photoalbum decreased from 4.8 to 2.9 seconds


• time switching between thumbnailpages decreased from 1.3 to 0.3 seconds


• the general loading/parsing-time of JavaScript decreased from 1,2 to 0.6 respectively 0.5 to 0.3 seconds (Firefox).

Once we released the tweaks, the pageviews per visit increased by 20%.