gistfile1.rb

require 'benchmark'
require 'strscan'

s = "this " * 20

puts "with .scan.each"
puts Benchmark.measure {
  100000.times do
    s.scan(/\w+[ $]/)
  end
}

GC.start

puts "with StringScanner"
puts Benchmark.measure {
  100000.times do
    parts = []
    ss = StringScanner.new(s)
    while part = ss.scan(/\w+[ $]/)
      parts << part
    end
  end
}

# jruby ss.rb 
# with .scan.each
#   2.750000   0.000000   2.750000 (  2.700000)
# with StringScanner
#   3.110000   0.000000   3.110000 (  3.110000)

# ruby ss.rb 
# with .scan.each
#   2.980000   0.020000   3.000000 (  3.029403)
# with StringScanner
#   2.800000   0.020000   2.820000 (  2.839481)