Much of what Rails provides to get your apps up and running isn’t optimized for performance. It’s crafted to be more efficient for developers, not more efficent at runtime. before_filter callbacks on your RESTful controllers to get the current object? That’s an extra database call. All those nifty plugins you are using to kickstart your app? They probably generate far more SQL (and slower SQL) than if you coded the same functionality ad-hoc. ActiveRecord itself is slow compared to raw SQL and object instantiation.