That way you don’t have to wait for the waiter to return from the kitchen because there are more waiters attending to you simultaneously. You can finish your meal faster if more than just one waiter is serving you. The time spent with “everything else” compared to the time spent with the actual transfer is too big, the overhead becomes significant. When you are transferring small files, the transferring itself takes almost no time, just as eating a pea, but the computation and communication time is the same as with big files. Because the pea is so small, you can eat it very fast, but if you want to eat more peas, first you have to pay for the first pea and only after that can you order a new one. You have to make the same routine as described above but all you will get at a time is a single pea. Transferring small files is like ordering peas one by one at the restaurant. It takes time to build up, to handle and to end the communication with the remote server just as ordering and paying at the restaurant take time. In the case of the file transfer, the overhead is the indirect computation and communication time that is required to perform the file transfer. Transferring the file equals the consumption of the food, everything before and after the meal is what we call the overhead. When you have finished your meal, you have to wait for the waiter to clear the table and then you can ask for the bill, and you can only leave after you have paid. In a restaurant, you take a seat, wait for the waiter, order a drink, go over the menu and then you order your meal. Eating at a restaurant has its rules, just as the different file transfer protocols have their own rules.

You might better understand the process by imagining it like eating at a restaurant.

Before I tell you how one file transfer client can be faster than the other, let me explain how transferring files works.

Cyberduck ftp cnet