php websocket server and clients

Hi all, I'm trying to build a script that creates a websocket server and some clients that connects to it. A huge synthesis of the code could be: |$server= stream_socket_server("tcp://127.0.0.1:8080"); for ($i= 1; $i<= 50; $i++) {

    var_dump($i);
    stream_socket_client("tcp://127.0.0.1:8080");

}| everything is fine for the first 35 clients, then the connections start to slow down and they happen almost one per second. What is the reason for these delays? Is it a configuration setting? Something due to my operative system? I'm using PHP 5.6.4-4 on ubuntu 15.04 Thanks!