https://github.com/rails/rails/pull/15443

gistfile1.rb

require 'abstract_unit'
require 'benchmark/ips'
require 'ruby-prof'

class AController < ActionController::Base
  def index
    render html: 'ok'
  end
end

class AController1Test < ActionDispatch::IntegrationTest
  def test_profile
    head 'https://www.example.com/a/index'
    assert_equal "", response.body
  end
end

Benchmark.ips(30) do |bm|
  bm.report 'Fast' do
    Minitest.run_one_method(AController1Test, 'test_profile')
  end
end

# Performance

Calculating -------------------------------------
                Slow        84 i/100ms
-------------------------------------------------
                Slow      887.1 (±13.9%) i/s -      26124 in  30.035717s
Calculating -------------------------------------
                Slow        84 i/100ms
-------------------------------------------------
                Slow      899.9 (±13.4%) i/s -      26544 in  30.036576s
Calculating -------------------------------------
                Slow        82 i/100ms
-------------------------------------------------
                Slow      917.1 (±16.2%) i/s -      26732 in  29.995072s

Calculating -------------------------------------
                Fast        93 i/100ms
-------------------------------------------------
                Fast      954.3 (±16.6%) i/s -      27807 in  30.014775s
Calculating -------------------------------------
                Fast        90 i/100ms
-------------------------------------------------
                Fast      958.2 (±16.3%) i/s -      27900 in  29.984117s
Calculating -------------------------------------
                Fast        90 i/100ms
-------------------------------------------------
                Fast      925.3 (±17.7%) i/s -      26910 in  30.093053s