Does anybody know if they have a not-slow VM/interpreter now? I read that they were replacing the old-and-slow tree traversing for a VM or something, but i've not heard much about it.
MRI has been replaced with YARV, which is sometimes much, much faster, and sometimes a little bit slower.
With JRuby, MacRuby, Gemstone, and other things in the pipeline, there are plenty of choices to go around.