Set#include? vs Hash#include? vs Hash#[]

bench.rb

require 'benchmark'
require 'set'

[10000, 100000, 1000000].each do |length|
  Benchmark.bmbm do |x|
    a = (1..length).to_a
    s = Set.new(a)
    h = Hash[a.zip([true]*a.length)]

    puts "\n\nSearching through #{length} elements"
    x.report('Set#include?')  { 10000000.times { s.include? rand(200) } }
    x.report('Hash#include?') { 10000000.times { h.include? rand(200) } }
    x.report('Hash#[]')       { 10000000.times { h[rand(200)] } }
  end
end

results.txt

Searching through 10000 elements
Rehearsal -------------------------------------------------
Set#include?    4.510000   0.000000   4.510000 (  4.521795)
Hash#include?   3.930000   0.010000   3.940000 (  3.939783)
Hash#[]         3.610000   0.000000   3.610000 (  3.627755)
--------------------------------------- total: 12.060000sec

                    user     system      total        real
Set#include?    4.520000   0.010000   4.530000 (  4.529696)
Hash#include?   3.910000   0.010000   3.920000 (  3.918378)
Hash#[]         3.570000   0.000000   3.570000 (  3.579173)


Searching through 100000 elements
Rehearsal -------------------------------------------------
Set#include?    4.490000   0.010000   4.500000 (  4.500315)
Hash#include?   3.860000   0.010000   3.870000 (  3.865276)
Hash#[]         3.540000   0.000000   3.540000 (  3.560600)
--------------------------------------- total: 11.910000sec

                    user     system      total        real
Set#include?    4.500000   0.020000   4.520000 (  4.594239)
Hash#include?   3.860000   0.030000   3.890000 (  4.365213)
Hash#[]         3.560000   0.010000   3.570000 (  3.653756)


Searching through 1000000 elements
Rehearsal -------------------------------------------------
Set#include?    4.700000   0.000000   4.700000 (  4.710997)
Hash#include?   4.190000   0.010000   4.200000 (  4.206315)
Hash#[]         3.780000   0.010000   3.790000 (  3.784912)
--------------------------------------- total: 12.690000sec

                    user     system      total        real
Set#include?    4.690000   0.010000   4.700000 (  4.709617)
Hash#include?   4.130000   0.010000   4.140000 (  4.142423)
Hash#[]         3.740000   0.000000   3.740000 (  3.742781)