I've started using the High Performance SSH/SCP - HPN-SSH from the PITTSBURGH SUPERCOMPUTING CENTER https://www.psc.edu/index.php/hpn-ssh
This flies compared to openssh, even when the target client or server doesn't have the patch.
I patched and built OpenSSH 5 for Solaris 8 through 10 then installed it on my PC from <invalid hyperlink removed by admin>
Even greater speed can be obtained using the "none" cipher for transfering non-critical files, encrypted files or tranfers within your local network where security is not an issue.
All of our servers have FTP and RCP shut off and a separate maintenance network that isn't exposed. Transfering large files (installation and upgrades) across the maintenance network using no cipher cuts transfer time and cpu load.