Shows how much slower Random.new.rand() is vs. Kernel's rand()

rand_benchmarker.rb

require 'benchmark'

NUM_TIMES = 10000

Benchmark.bmbm do |x|
  x.report("Random.new") do
    NUM_TIMES.times do
      Random.new.rand(2.0...4.0)
    end
  end

  x.report("rand") do
    NUM_TIMES.times do
      rand(2.0...4.0)
    end
  end
end