As a member of Matz's team in Heroku, I'm working Ruby 2.0 to be released in next February. Ruby 2.0 doesn't have drastic changes in behavior except adding some new features. However, an internal of Ruby 2.0 VM is changing to improve performance! For example, we changed VM data structures and method invocation processes to achieve fast execution. In this presentation, I will introduce the internal changes and its performance.