Comment by WalkingDead

Here is a step by step comparison on how cutting off ruby's features can make the JRuby implementation faster, from the guy who worked on JRuby.

http://blog.headius.com/2009/04/how-jruby-makes-ruby-fast.ht...

Read it, you will find it interesting. The guy also wrote a small language called Duby which used Ruby like syntax but is much more faster, because he didn't include any of those slowing down features.