There is also a good write-up [0] by Julia Evans. We ran into this with DICOM storescp, which is a chatty protocol and TCP_NODELAY=1 makes the throughput significantly better. Since DICOM is often used in a LAN, that default just makes it unnecessarily worse.
[0]: https://jvns.ca/blog/2015/11/21/why-you-should-understand-a-...