Debugging the performance of a Rails controller action

debug.rb

require 'rails/console/app'

ActiveSupport::Notifications.subscribe /^sql\./ do |*args|
  puts caller.grep(%r[/garmz/]) { |line| "    #{line.gsub(/.*?\/garmz\//, '')}" }.take(3) * "\n"
end

ActiveRecord::Base.logger = Logger.new(STDOUT)
app.get '/newsfeed'
ActiveRecord::Base.logger = Logger.new(nil)

Benchmark.bm do |b|
  b.report do
    5.times { app.get '/newsfeed' }
  end
end