Both FTP and HTTP use TCP as the transport protocol. The inherent characteristics of TCP make it highly susceptible to network latency and packet loss. Even on a relatively stable network, TCP goodput is always lower than the actual available line speed.
For example, on a T3 network (45 Mbps) with packet loss of 0.1% and a delay of 10 ms, FTP transfers can peak at only 30 Mbps. In sharp contrast, an accelerated file transfer solution typically yields goodput of 44 Mbps—only slightly less than maximum available line speed.
When network conditions deteriorate to 2% packet loss and a delay of 150 ms, FTP transfers can be expected to perform at 450 Kbps, or 1% of the actual available bandwidth. The accelerated file transfer solution maintains its 44Mbps goodput.