Thank you for this bug report. To properly diagnose the problem, we
need a short but complete example script to be able to reproduce
this bug ourselves. 

A proper reproducing script starts with <?php and ends with ?>,
is max. 10-20 lines long and does not require any external 
resources such as databases, etc. If the script requires a 
database to demonstrate the issue, please make sure it creates 
all necessary tables, stored procedures etc.

Please avoid embedding huge scripts into the report.

Steps to reproduce:
1) Please download 32MB file from here:
http://media.mlgpro.com/uv/2007/0206/117/1Adc06430e456ca66f8f572f6a5fe69308X0J500O1.swf
2) Save the following PHP script in the same dir with the above downloaded file.
3) Change values for constants to reflect your dirs and passwords.
4) Run the script and time the amount it will take to complete (be prepared to spend 3 hours if you will run into the same problem as I have).
5) Now run any other FTP program to FTP the same file to the same server.
6) Compare times.

<?php
function ftp($file_name) {
  $conn_id = ftp_connect(FTP_SERVER);
  $login_result = ftp_login($conn_id, FTP_USERNAME, FTP_PASSWORD);
  if ($conn_id && $login_result) {
    set_time_limit(60 * 60 * 4); // 4 hours from now
    $upload = ftp_put($conn_id, FTP_PATH . $file_name, DIRECTORY_DESTINATION . $file_name, FTP_BINARY);
  }
  ftp_close($conn_id);
  if ($upload) { return TRUE; }
  return FALSE;
}

$file_name = "test.swf";
$started = time();
$uploaded = ftp($file_name);
$ttime = time() - $started;
if ($uploaded) {
  echo "CONGRATULATIONS!";
} else {
  echo "FAILED!";
}
echo " Total time took: $ttime seconds";
?>

Oops, I'm sorry, I forgot to define constants. Please put the following code on the second line of the code I just submitted above (right after <?php)

define('FTP_SERVER', '');
define('FTP_USERNAME', '');
define('FTP_PASSWORD', '');
define('FTP_PATH', ''); // where to put your file on the server
define('DIRECTORY_DESTINATION', ''); // where your file is currently located on your local machine

It takes less then a couple of minutes, which is the same result I get using any other FTP client.