.... maybe a little heretic: is there any way to tell ssh to forward data
without any encryption. (or using some very "light" cipher)?

I am experimenting with a central backup server that will get data from
many hosts at the same time via rsync+ssh.
While I am very concerned about access control (thus ssh/public key
authentification), the data is transfered over a network that can't
easily be eavesdropped, so the data encryption would be expendable.
After doing some tests, it looks like the additional CPU load caused
by data encryption might be too much ...

Peter Daum

P.S.: I had posted this question before; as I just noticed,
it was rejected with the comment
"Please tell the list which version and vendor of SSH you are using"
The machines in question (all Linux) run different versions of openssh
(version 4.1 ..4.7, Suse, Debian,or self-compiled); I hadn't noticed
a new option regarding this issue in newer versions ...