Minimizing Computations in your Rails App

I don't know, they've got a lot of code to gain a 1.5 second lookup speed on 10 million lookups!

To me, that sounds like over engineering. Even at Facebook scale, can we say we are talking 1/10 of a millisecond per lookup? Is it worth the extra performance gain?

At the same time? I'm surprised the hash lookup isn't faster.