The tests were carried out on a machine equipped with a processor AMD K6 450 MHz, of two operating systems, the version Mandrake 8.1 of Linux and Windows 98, and 128 Mo of RAM. These tests consisted in evaluating the profit of performance brought by the solutions of optimization to the processing times. Used tools Two tools able to measure the processing times of requests on a Web server were used : Apache Bench (ab) : tool provided in the distribution of Apache. It makes it possible to test the performances of any server by specifying a number of requests to send to the server with a concurrency level (simultaneity of the requests). If the concurrency level isn't specified, the tool sends a request, awaits the response, sends the following one, awaits the response, and so on until the sending of all the requests. It is also necessary to specify the URL of the document to which the requests apply (more infos...). httperf: tool similar to Apache Bench. It is necessary to specify the server name, the document name, and the number of requests. This tool allows in addition to define sessions: each session corresponds to a user and includes a number of requests to send as well as the time between each request. A rate of sessions creation can also be defined (more infos ...). The advantage of using two tools is to be able to compare measurements, and to see if times do not differ from one tool to another for the same test, what would tend to make think that one of the two tools provides distorted results. Test protocols