3_0_output.txt

[200,
 {"X-Frame-Options"=>"SAMEORIGIN",
  "X-XSS-Protection"=>"1; mode=block",
  "X-Content-Type-Options"=>"nosniff",
  "X-Download-Options"=>"noopen",
  "X-Permitted-Cross-Domain-Policies"=>"none",
  "Referrer-Policy"=>"strict-origin-when-cross-origin",
  "Content-Type"=>"text/html",
  "Cache-Control"=>"no-cache",
  "X-Request-Id"=>"9342103d-6d8a-4644-aabf-239da57ca359",
  "X-Runtime"=>"0.001139"},
 "#<Rack::BodyProxy:0x000055f03cedb110>"]
Warming up --------------------------------------
    basic controller   352.000  i/100ms
 callback controller   191.000  i/100ms
Calculating -------------------------------------
    basic controller      3.569k (± 1.3%) i/s -     17.952k in   5.030744s
 callback controller      1.804k (± 7.3%) i/s -      8.977k in   5.004902s

Comparison:
    basic controller:     3569.0 i/s
 callback controller:     1804.0 i/s - 1.98x  (± 0.00) slower

benchmark_controller_callback.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'actionpack'
  gem "rails"
  gem "stackprof"
  gem 'benchmark-ips'
end

require "rails"
require "action_controller/railtie"

ENV["RAILS_ENV"] = "production"

class BaseController < ActionController::Base
  N = ENV.fetch("N", 1000).to_i
  N.times do |i|
    class_eval "def foo#{i}; end"
  end

  class_eval <<~RUBY
    def index
      #{N.times.map { |i| "foo#{i}" }.join("\n") }
      head :ok
    end
  RUBY
end

class BasicController < BaseController
end

class CallbackController < BaseController
  before_action do
    # no nothing
  end
end

class MyApp < Rails::Application
  config.eager_load = true
  config.cache_classes = true
  config.secret_key_base = "secretsecretsecret"
  config.consider_all_requests_local = true
  config.public_file_server.enabled = false

  config.log_level = :warn
  routes.append do
    get '/basic', to: "basic#index"
    get '/callback', to: "callback#index"
  end
  initialize!
end

app = Rails.application

make_request = -> (path) {
  env = Rack::MockRequest.env_for("http://example.org/#{path}")
  status, headers, body = app.call(env)

  body.close if body.respond_to?(:close)
  unless status == 200
    puts body.map(&:to_s)
    raise
  end
  [status, headers, body.to_s]
}

pp make_request.call("/basic")

result = Benchmark.ips do |x|
  x.report "basic controller" do
    make_request.call("basic")
  end

  x.report "callback controller" do
    make_request.call("callback")
  end

  x.compare!
end

lazy_singleton_output.txt

[200,
 {"X-Frame-Options"=>"SAMEORIGIN",
  "X-XSS-Protection"=>"1; mode=block",
  "X-Content-Type-Options"=>"nosniff",
  "X-Download-Options"=>"noopen",
  "X-Permitted-Cross-Domain-Policies"=>"none",
  "Referrer-Policy"=>"strict-origin-when-cross-origin",
  "Content-Type"=>"text/html",
  "Cache-Control"=>"no-cache",
  "X-Request-Id"=>"9f9e31af-abb3-42e4-a796-ea03b8f807b5",
  "X-Runtime"=>"0.001149"},
 "#<Rack::BodyProxy:0x00007ffb92502220>"]
Warming up --------------------------------------
    basic controller   351.000  i/100ms
 callback controller   341.000  i/100ms
Calculating -------------------------------------
    basic controller      3.580k (± 1.3%) i/s -     17.901k in   5.001053s
 callback controller      3.512k (± 1.1%) i/s -     17.732k in   5.049550s

Comparison:
    basic controller:     3580.1 i/s
 callback controller:     3512.0 i/s - same-ish: difference falls within error

ruby_master_output.txt

[200,
 {"X-Frame-Options"=>"SAMEORIGIN",
  "X-XSS-Protection"=>"1; mode=block",
  "X-Content-Type-Options"=>"nosniff",
  "X-Download-Options"=>"noopen",
  "X-Permitted-Cross-Domain-Policies"=>"none",
  "Referrer-Policy"=>"strict-origin-when-cross-origin",
  "Content-Type"=>"text/html",
  "Cache-Control"=>"no-cache",
  "X-Request-Id"=>"53ed7c39-e22c-4f20-af8f-6444a59ebecc",
  "X-Runtime"=>"0.001090"},
 "#<Rack::BodyProxy:0x000055e322981dd0>"]
Warming up --------------------------------------
    basic controller   359.000  i/100ms
 callback controller   191.000  i/100ms
Calculating -------------------------------------
    basic controller      3.604k (± 0.7%) i/s -     18.309k in   5.080686s
 callback controller      1.794k (± 7.3%) i/s -      8.977k in   5.033098s

Comparison:
    basic controller:     3603.8 i/s
 callback controller:     1794.0 i/s - 2.01x  (± 0.00) slower