benchmark.rb

require 'rubygems'
require 'bcrypt'
require 'digest'
require 'benchmark'
require 'forgery'

password = Forgery(:basic).password(:at_least => 8, :at_most => 20)

Benchmark.bm do |x|
  x.report('md5   ') do
    1000000.times { Digest::MD5.hexdigest(password) }
  end

  x.report('sha1  ') do
    1000000.times { Digest::SHA1.hexdigest(password) }
  end

  x.report('bcrypt') do
    1000.times { BCrypt::Password.create(password) }
  end
end

results.txt

            user     system      total        real
md5     2.490000   0.050000   2.540000 (  2.574742)
sha1    2.590000   0.050000   2.640000 (  2.772350)
bcrypt 90.420000   0.290000  90.710000 ( 93.921260)