Your internet connection does not approach 72 Mbps, much less 100 Mbps, so I wouldn't worry about it.
If you're worried about file transfers, consider that not all monitoring programs (including the stock MS icon on the taskbar) take the overhead of the networking into account. For instance, if you're transfering a 10MB file, it will tell you how long that file takes to transfer .. and the speed ignores the overhead cost of the networking protocols, block headers, etc., because people are interested in how fast the file transfers, not how fast the file + overhead transfers. The loss that you're seeing is probably just the overhead.
And yes, TCP/IP can generate that much overhead .. this is one of the problems with building the internet on a protocol that is over 40 years old.