bar.rb

require "benchmark"

Benchmark.bm do |x|
  count = 1000
  data = [1, 2]

  x.report("case1") do
    count.times do
      _ = "#{data[0]} #{data[1]}"
    end
  end

  x.report("case2") do
    count.times do
      _ = data.to_s
    end
  end

  x.report("case3") do
    count.times do
      _ = data.join(" ")
    end
  end
end

case1 0.000424 0.000110 0.000534 ( 0.000531)
case2 0.003387 0.000013 0.003400 ( 0.003419)

   user     system      total        real

case1 0.000631 0.000150 0.000781 ( 0.000778)
case2 0.004301 0.000231 0.004532 ( 0.004553)
case3 0.001171 0.000000 0.001171 ( 0.001218)