alt Hacker News> SFTP is an encrypted protocol, so maybe those CPU cycles add up to a lot of extra work over time or slowdown. That… shouldn’t feel convincing to anyone who gives it more than 15 seconds of thought, but we all live with our eyes wide shut at times.
FWIW, I previously spent some time trying to get the maximum possible throughput when copying files between a Windows host and a Linux VM, and the encryption used by most protocols did actually become a bottleneck eventually. I expect this isn't a big factor on 1gbps ethernet, but I've never measured it.
The bottleneck with SFTP / SCP / SSH is usually the server software - SSH can multiplex streams, so it implements its own TCP-style sliding windows for channel data. Unfortunately OpenSSH and similar server implementations suffer from the exact same problems that TCP did, where the windows don't scale up to modern connection speeds, so the maximum data in-flight quickly gets limited at higher BDPs.
HPN-SSH[1] resolves this but isn't widely deployed.
[1] https://www.psc.edu/hpn-ssh-home/