rshbench is a really trivial program written by Robert G. Brown designed to benchmark remote shells. The idea was to determine how much of a "penalty" was associated with using e.g. ssh as a secure and feature-rich remote shell versus the older, insecure, and feature poor rsh. It is preserved here because there is a small chance that this might once again be useful to somebody. I personally think that using ssh is a no-brain decision, though, for nearly everybody.