Slow transfers and long transfer durations can be caused by low network bandwidth, high network latency, large quantity of files being transferred, huge file sizes, network throttling, remote system performance, local system performance, encryption methods, and session time limits.

The physical limitations of a network or system cannot be circumvented. For example, if sending a 10GB file across the internet to the remote server takes you 2 hours then sending the same 10GB file across the internet to the remote server will take us 2 hours also, assuming we both have identical network connectivity with the remote server.