How to profile requests in a Rails 3 application

Question

How to profile requests in a Rails 3 application?

This answer seems to only work in 2.*. How should I do this in Rails 3?

Answer 1

I usually use https://github.com/newrelic/rpm new relic. It tells you which is the slowest call on render and it also gives you which line in your code does just that. Very informative and easy to use.