Testing the <23 string issue

benchmark.rb

require 'benchmark'

ITERATIONS = 1000000

Benchmark.bm(10) do |bench|
  0.upto(40) do |n|
    bench.report("chars: #{n}") do
      string = "n"*n
      ITERATIONS.times do
        string + 'x'
      end
    end
  end
end

my_output.txt

                 user     system      total        real
chars: 0     0.290000   0.000000   0.290000 (  0.285873)
chars: 1     0.320000   0.000000   0.320000 (  0.316728)
chars: 2     0.290000   0.000000   0.290000 (  0.292130)
chars: 3     0.290000   0.000000   0.290000 (  0.293374)
chars: 4     0.310000   0.000000   0.310000 (  0.306900)
chars: 5     0.300000   0.000000   0.300000 (  0.297575)
chars: 6     0.310000   0.000000   0.310000 (  0.314241)
chars: 7     0.300000   0.000000   0.300000 (  0.300243)
chars: 8     0.280000   0.000000   0.280000 (  0.286060)
chars: 9     0.310000   0.000000   0.310000 (  0.309694)
chars: 10    0.300000   0.000000   0.300000 (  0.300977)
chars: 11    0.330000   0.000000   0.330000 (  0.327538)
chars: 12    0.300000   0.000000   0.300000 (  0.302438)
chars: 13    0.320000   0.010000   0.330000 (  0.312763)
chars: 14    0.280000   0.000000   0.280000 (  0.288715)
chars: 15    0.300000   0.000000   0.300000 (  0.294411)
chars: 16    0.300000   0.000000   0.300000 (  0.303953)
chars: 17    0.310000   0.000000   0.310000 (  0.305969)
chars: 18    0.300000   0.000000   0.300000 (  0.308357)
chars: 19    0.310000   0.000000   0.310000 (  0.303445)
chars: 20    0.310000   0.000000   0.310000 (  0.314546)
chars: 21    0.310000   0.000000   0.310000 (  0.304749)
chars: 22    0.300000   0.000000   0.300000 (  0.307125)
chars: 23    0.470000   0.000000   0.470000 (  0.470054)
chars: 24    0.500000   0.000000   0.500000 (  0.501440)
chars: 25    0.530000   0.000000   0.530000 (  0.524160)
chars: 26    0.510000   0.000000   0.510000 (  0.512369)
chars: 27    0.490000   0.000000   0.490000 (  0.495345)
chars: 28    0.490000   0.000000   0.490000 (  0.489927)
chars: 29    0.520000   0.000000   0.520000 (  0.522215)
chars: 30    0.500000   0.000000   0.500000 (  0.501139)
chars: 31    0.490000   0.010000   0.500000 (  0.491002)
chars: 32    0.500000   0.000000   0.500000 (  0.497039)
chars: 33    0.520000   0.000000   0.520000 (  0.522955)
chars: 34    0.490000   0.000000   0.490000 (  0.485230)
chars: 35    0.480000   0.000000   0.480000 (  0.482624)
chars: 36    0.480000   0.000000   0.480000 (  0.477754)
chars: 37    0.510000   0.000000   0.510000 (  0.514367)
chars: 38    0.500000   0.000000   0.500000 (  0.506686)
chars: 39    0.570000   0.000000   0.570000 (  0.572416)
chars: 40    0.560000   0.000000   0.560000 (  0.563307)

output.txt

                 user     system      total        real
chars: 0     0.370000   0.000000   0.370000 (  0.366730)
chars: 1     0.380000   0.000000   0.380000 (  0.382128)
chars: 2     0.390000   0.000000   0.390000 (  0.387196)
chars: 3     0.370000   0.000000   0.370000 (  0.374867)
chars: 4     0.370000   0.000000   0.370000 (  0.370998)
chars: 5     0.370000   0.000000   0.370000 (  0.366505)
chars: 6     0.360000   0.000000   0.360000 (  0.364901)
chars: 7     0.380000   0.000000   0.380000 (  0.376964)
chars: 8     0.360000   0.000000   0.360000 (  0.361423)
chars: 9     0.360000   0.000000   0.360000 (  0.362585)
chars: 10    0.370000   0.000000   0.370000 (  0.364726)
chars: 11    0.370000   0.000000   0.370000 (  0.365690)
chars: 12    0.370000   0.000000   0.370000 (  0.374387)
chars: 13    0.360000   0.000000   0.360000 (  0.362398)
chars: 14    0.370000   0.000000   0.370000 (  0.365708)
chars: 15    0.360000   0.000000   0.360000 (  0.365309)
chars: 16    0.370000   0.000000   0.370000 (  0.364021)
chars: 17    0.360000   0.000000   0.360000 (  0.366792)
chars: 18    0.370000   0.000000   0.370000 (  0.369290)
chars: 19    0.370000   0.000000   0.370000 (  0.370876)
chars: 20    0.380000   0.000000   0.380000 (  0.375445)
chars: 21    0.380000   0.000000   0.380000 (  0.379652)
chars: 22    0.380000   0.000000   0.380000 (  0.382292)
chars: 23    0.570000   0.000000   0.570000 (  0.563633)
chars: 24    0.550000   0.000000   0.550000 (  0.552596)
chars: 25    0.540000   0.000000   0.540000 (  0.545093)
chars: 26    0.560000   0.000000   0.560000 (  0.560197)
chars: 27    0.590000   0.000000   0.590000 (  0.591256)
chars: 28    0.580000   0.000000   0.580000 (  0.572981)
chars: 29    0.580000   0.000000   0.580000 (  0.580868)
chars: 30    0.570000   0.000000   0.570000 (  0.570096)
chars: 31    0.560000   0.000000   0.560000 (  0.560095)
chars: 32    0.540000   0.000000   0.540000 (  0.547976)
chars: 33    0.550000   0.000000   0.550000 (  0.548256)
chars: 34    0.560000   0.010000   0.570000 (  0.556874)
chars: 35    0.570000   0.000000   0.570000 (  0.575082)
chars: 36    0.560000   0.000000   0.560000 (  0.560576)
chars: 37    0.560000   0.000000   0.560000 (  0.558877)
chars: 38    0.560000   0.000000   0.560000 (  0.562131)
chars: 39    0.580000   0.000000   0.580000 (  0.581959)
chars: 40    0.580000   0.000000   0.580000 (  0.575950)