Processando grandes quantidades de dados em PHP sem tempo limite do navegador

Eu escreveria dois scripts:

Arquivo index.php :

<iframe src="job.php" frameborder="0" scrolling="no" width="1" height="1"></iframe>
<script type="text/javascript">
    function progress(percent){
        document.getElementById('done').innerHTML=percent+'%';
    }
</script><div id="done">0%</div>

Arquivo job.php :

set_time_limit(0);                   // ignore php timeout
ignore_user_abort(true);             // keep on going even if user pulls the plug*
while(ob_get_level())ob_end_clean(); // remove output buffers
ob_implicit_flush(true);             // output stuff directly
// * This absolutely depends on whether you want the user to stop the process
//   or not. For example: You might create a stop button in index.php like so:
//     <a href="javascript:window.frames[0].location='';">Stop!</a>
//     <a href="javascript:window.frames[0].location='job.php';">Start</a>
// But of course, you will need that line of code commented out for this feature to work.

function progress($percent){
    echo '<script type="text/javascript">parent.progress('.$percent.');</script>';
}

$total=count($mobiles);
echo '<!DOCTYPE html><html><head></head><body>'; // webkit hotfix
foreach($mobiles as $i=>$mobile){
    // send sms
    progress($i/$total*100);
}
progress(100);
echo '</body></html>'; // webkit hotfix