delegator_bench.rb

require "delegate"

class BankAccount
  def number
    123456
  end
end

class SimpleDelegatorBankAccount < SimpleDelegator
end

class DelegateClassBankAccount < DelegateClass(BankAccount)
end

class ManualDelegatorBankAccount
  def initialize(target)
    @target = target
  end

  def number
    @target.number
  end
end

account = BankAccount.new
sdba = SimpleDelegatorBankAccount.new(account)
dcba = DelegateClassBankAccount.new(account)
mdba = ManualDelegatorBankAccount.new(account)

require "benchmark"

puts RUBY_VERSION

n = 1_000_000
Benchmark.bmbm(20) do |x|
  x.report("direct call") do
    n.times do
      _ = account.number
    end
  end
  x.report("manual delegation") do
    n.times do
      _ = mdba.number
    end
  end
  x.report("SimpleDelegator") do
    n.times do
      _ = sdba.number
    end
  end
  x.report("DelegateClass") do
    n.times do
      _ = dcba.number
    end
  end
end

# >> 2.2.0
# >> Rehearsal --------------------------------------------------------
# >> direct call            2.210000   0.020000   2.230000 (  2.332280)
# >> manual delegation      3.410000   0.070000   3.480000 (  3.500194)
# >> SimpleDelegator        2.850000   0.060000   2.910000 (  2.920977)
# >> DelegateClass          3.370000   0.020000   3.390000 (  3.411052)
# >> ---------------------------------------------- total: 12.010000sec
# >> 
# >>                            user     system      total        real
# >> direct call            1.800000   0.030000   1.830000 (  1.834531)
# >> manual delegation      2.830000   0.130000   2.960000 (  2.958950)
# >> SimpleDelegator        2.960000   0.040000   3.000000 (  3.038120)
# >> DelegateClass          2.390000   0.030000   2.420000 (  2.878221)

This is why I love benchmark-ips so much – does the right amount of running, shows standard deviation and a comparison. Three subsequent runs on MRI 2.2.0-p0 and i7-3517U:

chastell@devielle:~/coding/delegator_bench* master$ ruby delegator_bench.rb 
2.2.0
Calculating -------------------------------------
         direct call   154.655k i/100ms
   manual delegation   147.608k i/100ms
     SimpleDelegator    83.301k i/100ms
       DelegateClass   100.088k i/100ms
-------------------------------------------------
         direct call      7.624M (± 0.9%) i/s -     38.200M
   manual delegation      5.441M (± 0.8%) i/s -     27.307M
     SimpleDelegator      1.821M (± 0.4%) i/s -      9.163M
       DelegateClass      2.274M (± 1.7%) i/s -     11.410M

Comparison:
         direct call:  7624038.2 i/s
   manual delegation:  5440655.5 i/s - 1.40x slower
       DelegateClass:  2274447.1 i/s - 3.35x slower
     SimpleDelegator:  1821140.0 i/s - 4.19x slower

chastell@devielle:~/coding/delegator_bench* master$ ruby delegator_bench.rb 
2.2.0
Calculating -------------------------------------
         direct call   147.330k i/100ms
   manual delegation   140.938k i/100ms
     SimpleDelegator    89.453k i/100ms
       DelegateClass   101.876k i/100ms
-------------------------------------------------
         direct call      7.770M (± 0.8%) i/s -     38.895M
   manual delegation      5.511M (± 1.0%) i/s -     27.624M
     SimpleDelegator      2.255M (± 0.7%) i/s -     11.361M
       DelegateClass      2.511M (± 0.4%) i/s -     12.633M

Comparison:
         direct call:  7770463.0 i/s
   manual delegation:  5511189.7 i/s - 1.41x slower
       DelegateClass:  2510641.3 i/s - 3.10x slower
     SimpleDelegator:  2255441.7 i/s - 3.45x slower

chastell@devielle:~/coding/delegator_bench* master$ ruby delegator_bench.rb 
2.2.0
Calculating -------------------------------------
         direct call   155.063k i/100ms
   manual delegation   147.376k i/100ms
     SimpleDelegator    82.357k i/100ms
       DelegateClass    99.892k i/100ms
-------------------------------------------------
         direct call      7.648M (± 1.1%) i/s -     38.301M
   manual delegation      5.525M (± 0.9%) i/s -     27.707M
     SimpleDelegator      1.819M (± 0.9%) i/s -      9.142M
       DelegateClass      2.213M (± 0.5%) i/s -     11.088M

Comparison:
         direct call:  7647978.9 i/s
   manual delegation:  5525266.9 i/s - 1.38x slower
       DelegateClass:  2212954.9 i/s - 3.46x slower
     SimpleDelegator:  1818685.7 i/s - 4.21x slower