Ruby code for benchmarking JSON generation from Rails models. You need to install these gems before running: `gem install rails rabl jbuilder roar ffaker`. Based on https://gist.github.com/mimosa/ac14b3527c33bf767dc11875ce3964b8

json_benchmark.rb

require 'bundler'
require 'active_model_serializers'
require 'roar/decorator'
require 'roar/json'
require 'rabl'
require 'jbuilder'
require 'benchmark'
require 'ffaker'

class Post
  include ActiveModel::Model
  include ActiveModel::Serializers::JSON

  attr_accessor :id, :author, :body, :draft
end

posts = []

(1..100_000).each do |id|
  posts << Post.new(id: id, author: FFaker::Name.name, body: FFaker::HipsterIpsum.paragraph, draft: [true, false].sample)
end

class PostSerializer < ActiveModel::Serializer
  attributes :id, :author, :body, :draft
end

module PostsRepresenter
  include Roar::JSON

  property :id
  property :author
  property :body
  property :draft
end

def rabl_template
  '
    collection @posts
    attributes :id, :author, :body, :draft
  '
end

puts '_' * 88

def ams_test(posts)
  ActiveModel::Serializer::CollectionSerializer.new(posts, each_serializer: PostSerializer).to_json
end

def roar_test(posts)
  PostsRepresenter.for_collection.prepare(posts).to_json
end

def rabl_test(posts)
  Rabl.render(posts, rabl_template)
end

def jbuilder_test(posts)
  Jbuilder.encode do |json|
    json.array! posts, :id, :author, :body, :draft
  end
end

def to_json_test(posts)
  posts.map(&:to_json).to_json
end

puts 'with 100_000 records'

Benchmark.bm do |x|
  x.report('AMS') { ams_test(posts) }
  x.report('Roar') { roar_test(posts) }
  x.report('RABL') { rabl_test(posts) }
  x.report('JB') { jbuilder_test(posts) }
  x.report('to_json') { to_json_test(posts) }
end

puts "with 2000 records"

first2k = posts.take(2000)

Benchmark.bm do |x|
  x.report('AMS') { ams_test(first2k) }
  x.report('Roar') { roar_test(first2k) }
  x.report('RABL') { rabl_test(first2k) }
  x.report('JB') { jbuilder_test(first2k) }
  x.report('to_json') { to_json_test(first2k) }
end