On a Debian Stretch system, Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz, 'scp'ing files via the loopback interface, the fastest combination in the stock openssh/o

On a Debian Stretch system, Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz, 'scp'ing files via the loopback interface, the fastest combination in the stock openssh/opensshd is ciphers=aes128-gcm@openssh.com. The run-to-run variation of the various macs was big enough that I can't declare a winner, but umac-128@openssh.com and hmac-sha2-512-etm@openssh.com came out on top in two trials. Best rate over all trials: 976.6MB/s (= 7812Mb/s) though I don't know whether ssh is reporting powers-of-10 MBs or powers-of-2 MiBs... meanwhile, nc-over-loopback is is over 3400MB/s (27388Mb/s).