Benchmark of Various Ways to Fill an Array

fill-array.rb

require 'benchmark'

def bench
  Benchmark.measure do
    1_000_000.times { yield }
  end.real
end

array = Array.new 10

bench { array.fill 'x' }
# => 0.277697

bench { array.map { 'x' } }
# => 2.398355

bench { array.map! { 'x' } }
# => 2.016466

bench { ['x'] * array.size }
# => 0.787285

bench { Array.new array.size { 'x' } }
# => 0.542437

RUBY_VERSION
# => "2.0.0"