THE PAST DECADE has seen an increased interest in website performance, with businesses of all sizes realizing that even modest changes in page loading times can have a significant effect on their profits. The move toward a faster web has been driven largely by Yahoo! and Google, which have both carried out extensive research on the subject of website performance, and have worked hard to make web masters aware of the benefits.

This book provides valuable information that you must know about website performance optimization — from database replication and web server load balancing, to JavaScript profiling and the latest features of Cascading Style Sheets 3 (CSS3). You can discover (perhaps surprising) ways in which your website is under-performing, and learn how to scale out your system as the popularity of your site increases.


At first glance, it may seem as if website loading speeds aren’t terribly important. Of course, it puts off users if they must wait 30 seconds for your page to load. But if loading times are relatively low, isn’t that enough? Does shaving off a couple of seconds from loading times actually make that much of a difference? Numerous pieces of research have been carried out on this subject, and the results are quite surprising.

In 2006, Google experimented with reducing the size of its Maps homepage (from 100 KB to 70–80 KB). Within a week, traffic had increased by 10 percent, according to ZDNet ( ...

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