A ruby benchmark to simulate method lookup slowdown by dynamic method definition (in Ruby 2.1.2)

different_class.rb

require 'benchmark'

class Test

  mcount = 1000

  mcount.times do |i|
    class_eval "def method#{i}; end"
  end

  class_eval "def many_method_calls; #{ mcount.times.map { |i| "method#{i};" }.join } end"
end

class Test2; end

n = 10000
t = Test.new

Benchmark.bm do |b|

  b.report 'method definition only' do
    n.times do |i|
      Test2.class_eval "def test#{i}; end"
    end
  end
  b.report 'method definition and call' do
    n.times do |i|
      Test2.class_eval "def test#{i}; end"
      t.many_method_calls
    end
  end
  b.report 'call only' do
    n.times do |i|
      t.many_method_calls
    end
  end
end

different_class_result

       user     system      total        real
method definition only  0.190000   0.010000   0.200000 (  0.201972)
method definition and call  0.860000   0.000000   0.860000 (  0.858854)
call only  0.640000   0.000000   0.640000 (  0.647640)

same_class.rb

require 'benchmark'

class Test

  mcount = 1000

  mcount.times do |i|
    class_eval "def method#{i}; end"
  end

  class_eval "def many_method_calls; #{ mcount.times.map { |i| "method#{i};" }.join } end"
end

n = 10000
t = Test.new

Benchmark.bm do |b|

  b.report 'method definition only' do
    n.times do |i|
      Test.class_eval "def test#{i}; end"
    end
  end
  b.report 'method definition and call' do
    n.times do |i|
      Test.class_eval "def test#{i}; end"
      t.many_method_calls
    end
  end
  b.report 'call only' do
    n.times do |i|
      t.many_method_calls
    end
  end
end

same_class_result

       user     system      total        real
method definition only  0.190000   0.010000   0.200000 (  0.194328)
method definition and call  1.690000   0.010000   1.700000 (  1.706964)
call only  0.600000   0.000000   0.600000 (  0.601261)