Don't loop through every file line. Use readfile instead, its faster. This is off the php site: http://php.net/manual/en/function.readfile.php
$file = $_GET["file"];
if (file_exists($file)) {
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header("Content-Type: application/force-download");
header('Content-Disposition: attachment; filename=' . urlencode(basename($file)));
// header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . filesize($file));
ob_clean();
flush();
readfile($file);
exit;
}
Make sure to sanitize your get variable as someone could download some php files...