Single vs Double quotes

strings.rb

require 'benchmark'
Benchmark.bmbm do |b|
  b.report("single") do
    10_000.times do
      'some string'
    end
  end
  b.report("double") do
    10_000.times do
      "some string"
    end
  end
  b.report("double 2") do
    10_000.times do
      "some string#{nil}"
    end
  end
  b.report("single") do
    10_000.times do
      'some string'
    end
  end
end
__END__
Rehearsal --------------------------------------------
single     0.000000   0.000000   0.000000 (  0.002007)
double     0.010000   0.000000   0.010000 (  0.001456)
double 2   0.000000   0.000000   0.000000 (  0.006717)
single     0.000000   0.000000   0.000000 (  0.000993)
----------------------------------- total: 0.010000sec

               user     system      total        real
single     0.000000   0.000000   0.000000 (  0.000994)
double     0.000000   0.000000   0.000000 (  0.000814)
double 2   0.010000   0.000000   0.010000 (  0.004737)
single     0.000000   0.000000   0.000000 (  0.000843)