problems with the speed of transmission w5100

I use the code taken from the FTP playground, I ran into the problem that the transmission speed is very small at a speed of about 50 kbps, how can I increase the speed?
ethernet shield w5100
and arduino 2560
thank you in advance

The only way you can increase the speed is use a faster board than the mega. Even then, you are limited by the speed of the SPI bus.