Object#extend vs proxy object performance

extend_vs_proxy.rb

require 'benchmark/ips'

class Foo
  def bar
    # "Foo#bar"
  end
end

module Bar
  def bar
    # "Bar#bar"
  end
end

class FooWrapper
  attr_reader :obj
  def initialize(obj)
    @obj = obj
  end

  def bar
    # "FooWrapper#bar"
  end

  def method_missing *args, &block
    obj.public_send *args, &block
  end
end

Benchmark.ips do |x|
  x.report "plain" do
    Foo.new.bar
  end

  x.report "extend" do
    Foo.new.extend(Bar).bar
  end

  x.report "proxy" do
    FooWrapper.new(Foo.new).bar
  end
end

# Calculating -------------------------------------
#                plain   135.946k i/100ms
#               extend    34.635k i/100ms
#                proxy   112.357k i/100ms
# -------------------------------------------------
#                plain      4.939M (± 5.0%) i/s -     24.742M
#               extend    438.022k (± 4.1%) i/s -      2.217M
#                proxy      2.676M (± 4.1%) i/s -     13.370M

Using Object#extend robs a whopping 90% of an object's performance by smashing the method cache. Using a proxy only slows it down by about 50%.