Comment by rapier1

More than 2 decades at this point. The primary reasons is that the full patch set would be a burden for them to integrate and they don't prioritize performance for bulk data transfers. Which is perfectly understandable from their perspective. HPN-SSH builds on the expertise of OpenSSH and we follow their work closely - when they make a new release we incorporate it and follow with our own release inside of a week or two (depending on how long the code review and functionality/regression testing takes). We focus on throughput performance which involves receive buffer normalization, private key cipher speed, code optimization, and so forth. We tend to stay clear of anything involve authentication and we never roll our own when it comes to the ciphers.