Benchmark: Array.empty? vs. Array.size == 0

gistfile1.rb

require 'benchmark'
Benchmark.bm do |x|
  empty = []
  not_empty = [:foo, :bar, :baz]
  # (size == 0) is faster than empty? for both empty
  # and non-empty arrays.
  x.report { 1000000.times  { empty.size == 0 } }
  x.report { 1000000.times { not_empty.size == 0 } }
  #    user     system      total        real
  # 0.100000   0.000000   0.100000 (  0.098931)
  # 0.100000   0.000000   0.100000 (  0.100634)
  
  x.report { 1000000.times  { empty.empty? } }
  x.report { 1000000.times  { not_empty.empty? } }
  #    user     system      total        real
  # 0.120000   0.000000   0.120000 (  0.137860)
  # 0.130000   0.010000   0.140000 (  0.129975)
end