By Jeroen Borgers More and more Internet users buy in web shops these days. Research shows that the part of European Internet users that buys on-line has grown from 40% in 2004 to 80% in 2008. Additionally, large web retailers in The Netherlands see their revenue grow just as if the recession has never materialized. Business seems to be flourishing. I also like to shop on the web. Now and then I enter a web shop where I have to wait before pages appear fully. Most of the time I’ll move away: with just one click I’m off to the competitor. The increased comparison possibilities and freedom of choice offered by the Internet are not only valid for the products, but also for the web shops themselves. Therefore, it has become crucial for the success of the web shop to have a responsive web site. With only a few concurrent visitors, it is usually not so hard to have a quick website. However, with the growing trend of Internet sales, the increasing integration and complexity of back-end systems and the by marketing demanded ever increasing richness of the user experience, this often becomes a big challenge for developers and operators. This may result in systems blacking out under high load or responding too slowly. So the question is: how can we prevent these performance and availability problems and how can we assure a web site is always quick and available? On the basis of real life, trial and error experience we’ve come to an approach which can be described as: measure, don’t guess; seven steps to performance success. I’ll explain this approach in the follow up blogs, and next time I'll first describe in which forms performance difficulties can present themselves. Stay tuned.