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require 'rubygems'

libraries = ['open-uri', 'rack', 'rest_client', 'activerecord', 'activesupport', 'heroku', 'net/http']
libraries = [libraries[2]] # this has to be manually tweaked

first_time = {}
later_time = {}

def time_it(&block)
  t = Time.now
  block.call
  Time.now - t
end

libraries.each do |lib|
  time = time_it do
    require lib
  end
  first_time[lib] = time

  n = 1000
  time = time_it do
    n.times { require lib }
  end
  time = time / n.to_f
  later_time[lib] = time
end

libraries.each do |lib|
  puts "#{lib}: initial: #{first_time[lib]}, subsequent: #{(first_time[lib]/later_time[lib]).round}x"
end