Attached please find a patch for PostgreSQL 9.4 which changes the maximum amount of data that the wal sender will send at any point in time from the hard-coded value of 128KiB to a user-controllable value up to 16MiB. It has been primarily tested under 9.4 but there has been some testing with 9.5.
In our lab environment and with a 16MiB setting, we saw substantially better network utilization (almost 2x!), primarily over high bandwidth delay product links.
