Well if there are JIT compilers for Ruby, then why isnt a JIT compiler included for the default ruby package? Or in other words, why Ruby hasnt implemented a JIT compiler at its core like node.js did, given its performance bottleneck as compared to other languages? As far as I know, on shared webhosts that provide ruby and ROR, their default installation of ruby does not have JIT compiler(while node.js on any webhost will have a JIT compiler bundled). You need to have at least a VPS or even dedicated server, to install Rubinius or JRuby, which means that ruby will at least be very slow on the majority of websites that use this language, since most websites are on shared hosts.