Embedding vs to_s and concat

def test()
  10.times do
    start_time = Time.now.to_f
    x = []
    1000000.times do |i|
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x << "foo#{i}"
      x = []
    end
    end_time = Time.now.to_f
    puts "Inline: #{end_time-start_time}"
    start_time = Time.now.to_f
    x = []
    1000000.times do |i|
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x << 'foo' + i.to_s
      x = []
    end
    end_time = Time.now.to_f
    puts "Concat: #{end_time-start_time}"
  end
end