Large file download taking more time - php

Question

I have used following code to download approximate 920MB file,
set_time_limit(0);
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Cache-Control: public");
header("Content-Description: File Transfer");
header("X-Sendfile: $zipname"); // For Large Files
header("Content-type: application/zip");
header("Content-Disposition: attachment; filename=\"".$zipname."\"");
header("Content-Transfer-Encoding: binary");
header("Content-Length: ".filesize($directory_location . '/' . $zipname));
ob_end_flush();
readfile($directory_location . '/' . $zipname);
Before this code i did some study with the following links Using X-Sendfile with Apache/PHP, Streaming a large file using PHP and Limit download speed using PHP but not much helpful to me because file download still takes more time with just (2MB) file. It's not showing and transfer rate or anything else. I want download start to serve file with around 60Kbps, with all files (Large or small)
UPDATE: One more thing i noticed its not showing any download process just executing and after sometime display the pop-up to choose the location, and after hitting save button its direct save to the computer without any downloading process window :(
Please help me to guide the right way.

Answer 1

Based on above comments there are two solutions:
1) Just download the file directly. You don't appear to be doing any validation, so if not, then just pass the user to the file to download and let apache handle it.
2) If you do need validation / pre-processing, then check mod_xsendfile - adding the header isn't enough, you actually need to add the mod to apache. If you're in Linux then compile from source (https://tn123.org/mod_xsendfile/). If you're not in Linux then mod_xsendfile for Win x64? has a response from the author saying he can provide binaries - but that's in 2010. There's a bit of advice around the web - although it's been a while since I looked at it so can't really help much more.