gistfile1.txt

              user     system      total        real
unpack:   0.000000   0.010000   0.010000 (  0.003435)
isutf8:   0.000000   0.030000   0.030000 (  0.032497)
regexp:   0.000000   0.000000   0.000000 (  0.000012)

validation_bench.rb

require 'benchmark'
require 'kconv'

$KCODE = 'u'

str = ARGF.read

Benchmark.bm(8) do |x|
  x.report('unpack: ') do
    str.unpack('U*')
  end
  x.report('isutf8: ') do
    str.isutf8
  end
  x.report('regexp: ') do
    /\A[\w\W]\z/ === str
  end
end