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?
Rack Mini Profiler is really good: https://github.com/SamSaffron/MiniProfiler/tree/master/Ruby
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.
Mike Lewis
Have you checked out the built in profiler?
来源：https://stackoverflow.com/questions/5302346/how-to-profile-requests-in-a-rails-3-application