In order to improve capacity and performance of Web oriented systems, several analytic and simulation models on the Web traffic are done. We present a tuning project of an existing Web system. We first propose a performance model based on classical queuing network theory. After statistical evaluation of the workload parameters, we establish some solutions for improving the system performance from a user's perspective. Then we show how the burstiness of the Web traffic can be translated in the previous Markovian model, allowing a better capacity and performance analysis. Voir le lien ici