A half century of software engineering says that you should write the code first and worry about making it faster only if it is too slow. Donald Knuth is right: Premature optimization is the root of all evil. Don’t let a little bit of insight into your Ruby implementation blind you to this fundamental truth. Your Ruby was fast enough yesterday, before you started poking around in its innards. It is still fast enough.
– Eloquent Ruby, Russ Olsen