Testing if it is faster to split an array by dup/shift/splat or index/index/splat

bench_array_split_methods.rb

require 'rubygems'
gem     'minitest'
require 'minitest/autorun'
require 'minitest/benchmark'

class Bench < MiniTest::Unit::TestCase
  def self.test_order
    :alpha
  end

  def self.bench_range
    bench_exp 1_000, 1_000_000
  end

  TABLE = {
    first: [:second, :third],
    one:   [:two, :three, :four],
  }

  def bench_lookup_dup_shift_splat
    assert_performance_linear 0.99 do |n|
      entry = TABLE[:first]
      n.times {
        thing = entry.dup
        thing.shift
        test = *thing
      }
      entry = TABLE[:one]
      n.times {
        thing = entry.dup
        thing.shift
        test = *thing
      }
    end
  end

  def bench_lookup_index_splat
    assert_performance_linear 0.99 do |n|
      entry = TABLE[:first]
      n.times {
        entry[0]
        test = *entry[1..-1]
      }
      entry = TABLE[:one]
      n.times {
        entry[0]
        test = *entry[1..-1]
      }
    end
  end
end

 Bench                               1000       10000   100000  1000000
 bench_lookup_dup_shift_splat      0.001170  0.011303    0.133173    1.356868
 bench_lookup_index_splat    0.000525    0.005105    0.077832    0.843958