Using NFS v4.2 on Arch, nfs-utils 2.3.3, linux 4.18.16. If a server has multiple nfs exports on different filesystems, and a client moves a file from one of these exports to another, the file contents transmit across the network. If the file contents were kept on the server, there would be a great speed boost. (Assuming the network speed is less than the server disk I/O speed.) Apologies if this is one of those things that sounds easy and has been asked a lot but rejected.
