为什么curl比浏览器中的请求慢

Question

I have a curl like this:

    $t1 = time();
    exec('echo $t1 >> debug');
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $service);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    $output = curl_exec($ch);
    curl_close($ch);
    $t2 = time();
    exec('echo $t2 >> debug');

when i execute the url in browser it is fast enough. but this curl is much slower(about 20 seconds later). how can i make it as fast as the simple request?

also i have these results when i get the curl_getinfo:

     connect_time: 0.01   //on average
     total_time: 0.24      //on average