cheap_strings.rb

module CheapStrings
  def `(str)
    str
  end
end

module A
  extend CheapStrings

  def self.make_lots_of_strings
    10_000_000.times do
      "hello world"
    end
  end

  def self.make_lots_of_cheap_strings
    10_000_000.times do
      `hello world`
    end
  end
end

require "benchmark"

Benchmark.bmbm do |b|
  b.report "strings" do
    A.make_lots_of_strings
  end

  b.report "cheap strings" do
    A.make_lots_of_cheap_strings
  end
end

# λ ruby cheap_strings.rb
# Rehearsal -------------------------------------------------
# strings         2.390000   0.000000   2.390000 (  2.389402)
# cheap strings   1.340000   0.000000   1.340000 (  1.346113)
# ---------------------------------------- total: 3.730000sec
#
#                     user     system      total        real
# strings         2.380000   0.000000   2.380000 (  2.384954)
# cheap strings   1.350000   0.000000   1.350000 (  1.350808)