gistfile1.txt

# create
def Bench.run
  string = ''
  5_000_000.times do
    StringScanner.new string
    string << '.'
  end
end

# create2
def Bench.run
  5_000_000.times do |i|
    StringScanner.new i.to_s
  end
end

Rubinius HEAD:

                                    user     system      total        real
create                          2.321300   0.012382   2.333682 (  2.410239)
create2                         2.233669   0.000398   2.234067 (  2.256402)


With this monkey patch:

  class StringScanner
    def initialize(string, dup=false)
      @string = StringValue(string)  # fix for issue 696: https://github.com/evanphx/rubinius/issues/#issue/696
      reset_state
    end
  end

I get:
                                   user     system      total        real
create                          2.115283   0.008810   2.124093 (  2.214133)
create2                         1.944784   0.003430   1.948214 (  1.979908)