Micro-benchmark to test different ways of adding Arrays

array_addition_benchmark.rb

#!/usr/bin/env ruby

require 'benchmark'

Benchmark.bm do |b|
  n = 1_000_000

  array1 = [1,2,3,4,5,6]
  array2 = [7,8,9,10,11,12,13,14]
  array3 = [15,16,17,18,19,20]

  b.report('array + array + ...') do
    n.times do
      array1 + array2 + array3
    end
  end

  b.report('[*array, *array, ...]') do
    n.times do
      [*array1, *array2, *array3]
    end
  end
end

output.txt

       user     system      total        real
array + array + ...  0.223602   0.000000   0.223602 (  0.225337)
[*array, *array, ...]  0.384585   0.005859   0.390444 (  0.393595)

If in place update is a viable option you could also use concat:

  b.report('array.concat(array, ...)') do
    n.times do
      array1.concat(array2, array3)
    end
  end

  b.report('array.concat(array).concat(array)...') do
    n.times do
      array1.concat(array2).concat(array3)
    end
  end

array + array + ...  0.140634   0.001944   0.142578 (  0.142576)
[*array, *array, ...]  0.297938   0.000000   0.297938 (  0.297953)
array.concat(array, ...)  0.227805   0.018993   0.246798 (  0.246806)
array.concat(array).concat(array)...  0.145018   0.021008   0.166026 (  0.166041)