Ruby String Concatenation Performance Test ('<<' operator vs '+' operator vs interpolation) http://ssut-dev.tumblr.com/post/82675129445/ruby-string-concatenation-ruby-2-1-1

benchmark.rb

require 'benchmark'

N = 10_000
LENGTH = 100

STR1, STR2, STR3 = "a", "b" * LENGTH, "c"
puts "LENGTH: " << (STR1.size + STR2.size + STR3.size).to_s

Benchmark.bm(10) do |x|
  x.report('"" < STR1 << STR2 << STR3') do
    N.times do
      y = '' < STR1 << STR2 << STR3
    end
  end
  
  x.report('STR1 + STR2 + STR3') do
    N.times do
      y = STR1 + STR2 + STR3
    end
  end
  
  x.report('#{STR1}#{STR2}#{STR3}') do
    N.times do
      y = "#{STR1}#{STR2}#{STR3}"
    end
  end
  
  x.report('[STR1, STR2, STR3].join') do
    N.times do
      y = [STR1, STR2, STR3].join
    end
  end
end

result.txt

- OS X 10.9 Mavericks / RubyENV(rbenv) 2.1.1-p76 -
LENGTH: 102
                 user     system      total        real
"" < STR1 << STR2 << STR3  0.000000   0.010000   0.010000 (  0.005643)
STR1 + STR2 + STR3  4.320000   6.910000  11.230000 ( 11.255716)
#{STR1}#{STR2}#{STR3}  2.450000   5.930000   8.380000 (  8.377277)
[STR1, STR2, STR3].join  2.080000   3.710000   5.790000 (  5.886817)

- Ubuntu 13.10 / RubyENV(rbenv) 2.1.1-p76 -
LENGTH: 102
                 user     system      total        real
"" < STR1 << STR2 << STR3  0.010000   0.000000   0.010000 (  0.004026)
STR1 + STR2 + STR3  2.270000   0.260000   2.530000 (  2.531887)
#{STR1}#{STR2}#{STR3}  1.230000   1.530000   2.760000 (  2.781068)
[STR1, STR2, STR3].join  0.970000   0.060000   1.030000 (  1.015118)