Performance testing Ruby's uniq

uniq_bench.rb

require 'rubygems'
require 'benchmark'

objects = ["string", %w(array), { :key => 'value' }, 9000] * 100

GC.disable

Benchmark.bm do |x|
  x.report('map => uniq') do
    10000.times { objects.map { |object| object.class }.uniq } 
  end
  x.report('uniq => map') do
    10000.times { objects.uniq { |object| object.class }.map { |object| object.class } } 
  end
end

# Ruby Enterprise Edition
#       user     system      total        real
# map => uniq  0.990000   0.010000   1.000000 (  1.010733)
# uniq => map  1.680000   0.020000   1.700000 (  1.690783)
# 
# Ruby 1.9.3 w/ performance patches
#        user     system      total        real
# map => uniq  2.170000   0.010000   2.180000 (  2.175190)
# uniq => map  1.440000   0.000000   1.440000 (  1.436704)
# 
# Ruby 2.0
#        user     system      total        real
# map => uniq  0.930000   0.010000   0.940000 (  0.941251)
# uniq => map  0.620000   0.000000   0.620000 (  0.618595)