title: Why is MRI the mainstream Ruby interpreter, while it performs the worst?
body: <p>Having seen <a href="http://engineering.twitter.com/2011/05/faster-ruby-kiji-update.html" rel="nofollow noreferrer">this interpreter comparison graph</a>, I wondered the reasons behind the MRI's mainstream usage, although it performs the worst. Why aren't <a href="http://engineering.twitter.com/2011/03/building-faster-ruby-garbage-collector.html" rel="nofollow noreferrer">Kiji</a> or <a href="http://blog.phusion.nl/2011/02/21/ruby-enterprise-edition-1-8-7-2011-02-released/" rel="nofollow noreferrer">Ruby Enterprise Edition</a> used more frequently; lack of gem support or something else?
  <img src="https://i.stack.imgur.com/kQG72.png" alt="Ruby comparison graph"></p>
  
  <p>For instance, Ruby Enterprise Edition is chosen by some of the most popular companies, thanks to its <a href="http://www.modrails.com/documentation/Users%20guide%20Nginx.html#_how_it_works" rel="nofollow noreferrer">copy-on-write feature</a>; I wonder if any other interpreter implements it.</p>
  
  <blockquote>
    <p>REE can be easily installed in
    parallel to your existing Ruby
    interpreter, allowing you switch to
    REE with minimal hassle or risk. REE
    has been out for several years now and
    is already used by many high-profile
    websites and organizations, such as
    <strong>New York Times</strong>, <strong>Twitter</strong>, <strong>Shopify</strong> and
    <strong>37signals</strong>.</p>
    
    <p>“We switched to enterprise ruby to get
    the full benefit of the
    [copy-on-write] memory characteristics
    and we can absolutely confirm the
    memory savings of 30% some others have
    reported. This is many thousand
    dollars of savings even at today’s
    hardware prices.”</p>
  </blockquote>