I am running into severe performance issues using SSH/Rsync on a Synology NAS (model DS413j if anybody knows anything about it).
sshd and the
rsync processes are taking 100% CPU on the NAS, and the transfer speed is about 6 or 7MB/s, which is far below the usual network speed -- a Gigabit link that works at more than 50MB/s between other computers on the network. This -- and multiple forum posts about the same kind of issues -- leads me to believe that the bottleneck is the SSH session encryption.
Is there a way to reduce the session key size (or to change to a faster algorithm if necessary)?