base58.rb

require 'benchmark/ips'
require 'securerandom'

n = 50
alphabet = ('0'..'9').to_a  + ('A'..'Z').to_a + ('a'..'z').to_a - ['0', 'O', 'I', 'l']
alphabet2 = ('0'..'9').to_a  + ('a'..'z').to_a

Benchmark.ips do |x|
  x.report("clever58") do
    SecureRandom.random_bytes(n).unpack("C*").map do |byte|
      idx = byte % 64
      idx = SecureRandom.random_number(58) if idx >= 58
      alphabet[idx]
    end.join
  end

  x.report("pedestrian58") do
    n.times.map { alphabet[SecureRandom.random_number(58)] }.join
  end

  x.report("suggested36") do
    SecureRandom.random_bytes(n).unpack("C*").map do |byte|
      idx = byte / 7
      idx = SecureRandom.random_number(36) if idx >= 36
      alphabet2[idx]
    end.join
  end

  x.report("clever36") do
    SecureRandom.random_bytes(n).unpack("C*").map do |byte|
      idx = byte % 64
      idx = SecureRandom.random_number(36) if idx >= 36
      alphabet2[idx]
    end.join
  end

  x.report("pedestrian36") do
    n.times.map { alphabet2[SecureRandom.random_number(36)] }.join
  end
end

output.txt

% ruby base58.rb
Warming up --------------------------------------
            clever58     1.004k i/100ms
        pedestrian58   148.000  i/100ms
         suggested36     2.653k i/100ms
            clever36   283.000  i/100ms
        pedestrian36   144.000  i/100ms
Calculating -------------------------------------
            clever58     11.291k (± 4.9%) i/s -     57.228k in   5.081750s
        pedestrian58      1.447k (± 5.5%) i/s -      7.252k in   5.027963s
         suggested36     28.269k (± 4.0%) i/s -    143.262k in   5.076386s
            clever36      3.072k (± 3.9%) i/s -     15.565k in   5.075289s
        pedestrian36      1.441k (± 2.6%) i/s -      7.200k in   5.000994s