While the Ruby 1.8 VM is quite slow, the YARV VM used in 1.9 is much faster, resulting in similar performance to most other dynamic languages. These tests are showing MacRuby being 3x faster than 1.9, which puts it in "quite fast" territory.
Programmers used to batch environments may find it hard to live without giant listings; we would find it hard to use them. -- D.M. Ritchie