问php、mysql、打开数据库时间太长

EN

echo "<BR>3 - ".(microtime(true)-$startTime);  #How long it takes for this page to do
$sqldb=open_database();  #Open the database
echo "<BR>4 - ".(microtime(true)-$startTime);  #How long it takes for this page to do

3 - 5.1140758991241
4 - 6.1172299385071

//This function is to open the database
function open_database() {
    //Now we will connect to the database
    $sqldb=mysql_connect($_SESSION['hostname'], $_SESSION['dbusername'], $_SESSION['password']) OR die ('Unable to connect to database! Please try again later.');
    mysql_select_db($_SESSION['dbname'], $sqldb);  #Select which database we wish to use - in this case the customer one

    if(empty($sqldb)) {  //If there is no database then we have an error - MASSIVE ERROR!
        header('Location:'.$_SESSION['web_site'].'/error.php');
        die();
    }
    return($sqldb);
}