Easy steps for CPU profiling a Rails app
- add ruby-prof to your gemfile (https://github.com/ruby-prof/ruby-prof)
- grab kcachegrind or qcachegrind (brew install qcachegrind graphviz on os x)
- plop development_profiler.rb in lib in your app
- wrap your questionable code in a prof block
- open the file in qcachegrind