This article addresses the problem of the study of the performance evaluation and behavior of the large scale Peer-to-Peer file sharing systems. In particular the impact of realistic workload is considered by evaluating the Freenet system. This evaluation is achieved by a simulation approach. A set of inputs is determined as well as their distribution law in order to generate a more realistic workload. One of them is an original characterization of user's requests. An other contribution is to show the impact of these more realistic inputs on the overall system performances. Notably new abrupt behaviors in the learning process are described.