One thing that causes the most slow down in Net::FTP is transferring in ASCII mode. In ASCII mode the file is transmitted over the net with lines ending in CRLF.

This means that Net::FTP, and the server, have to do some processing to add and remove the CR if the native text file format of the machine is to just have LF (i.e. UNIX machines).

So, if you know that the line endings in the file on the server are in the correct format for the client, then transfer in binary mode and you will see quite a speedup.

Another option that can speed things up is to use a larger blocksize for the transfer.