The code still needs some work. The main reason it will be slow is the way it transfers the file to the FTP server (not from it, that should be ok). Look for the "needs improvement" remark. It should buffer an array of characters and send them in one packet.
Feel free to modify it to meet your needs.
edit: Also try removing the Serial.print() of the file contents during the transfer. On a larger file, that could eat up some time too. That was put there for debugging only.