results.txt

       user     system      total        real
Forwardable  0.170000   0.000000   0.170000 (  0.167711)
Send         0.110000   0.000000   0.110000 (  0.106545)
Simple call  0.070000   0.000000   0.070000 (  0.070068)

test.rb

require 'benchmark'
require 'forwardable'

class TestForwardable
  extend Forwardable
  def_delegators :@array, :size

  def initialize
    @array = (1..100).to_a
  end
end

class TestMethod
  def initialize
    @array = (1..100).to_a
  end

  def size
    @array.size
  end
end

class TestSend
  def initialize
    @array = (1..100).to_a
  end

  def size
    @array.send(:size)
  end
end

forwardable = TestForwardable.new
sender = TestSend.new
method = TestMethod.new

Benchmark.bm do |x|
  x.report("Forwardable") { 1_000_000.times { forwardable.size } }
  x.report("Send") { 1_000_000.times { sender.size } }
  x.report("Simple call") { 1_000_000.times { method.size } }
end