fsockopen,fopen,file_get_contents 为啥fsockopen是最快的呢

fsockopen,fopen,file_get_contents 为什么fsockopen是最快的呢
query_time_class.inc.php

<?php

    class query_time_class{

        

        var $start_time;

        var $end_time;

        

        function query_start(){

            

            $this->start_time = 0;

            $this->end_time   = 0;

            $this->start_time = $this->get_cur_sec();

            

        }

        

        function query_end(){

            

            $this->end_time = $this->get_cur_sec();

            

        }

        

        function get_query_time(){

            

            $time = floatval($this->end_time - $this->start_time);

            $time = sprintf("%01.4f",$time);

            return $time;

            

        }

        

        function get_cur_sec(){

            

            list($msec,$sec) = explode(" ", microtime());

            $msec            = floatval($msec);

            $sec             = floatval($sec+$msec);

            return $sec;

            

        }

        function out_put(){

            

            $time   = $this->get_query_time();

            $output = "执行时间 {$time} 秒";

            echo $output;

            

        }

        

    } 





?>

执行代码