__autoload函数加载的文件夹多，网站流量又大，那么对速度影响大么

__autoload函数加载的文件夹多，网站流量又大，那么对速度影响大么！
function __autoload($className){
if(file_exists('model/'.$className.'.class.php')){
include_once('model/'.$className.'.class.php');
}
if(file_exists('Controller/'.$className.'.class.php')){
include_once('Controller/'.$className.'.class.php');
}

$prefix=$GLOBALS['groupName']=='main'?'':'../';
if(file_exists($prefix.'core/'.$className.'.class.php')){
include_once($prefix.'core/'.$className.'.class.php');
}
if(file_exists($prefix.'core/Smarty-3.1.6/'.$className.'.class.php')){
include_once($prefix.'core/Smarty-3.1.6/'.$className.'.class.php');
}
if(file_exists($prefix.'core/Smarty-3.1.6/sysplugins/'.$className.'.php')){
include_once($prefix.'core/Smarty-3.1.6/sysplugins/'.$className.'.php');
}

}