foo.rb

require 'benchmark/ips'

LONG_STRING = "   this is a longer test
      this is a longer test
      this is a longer test
      this is a longer test
      this is a longer test"

class String
  def original_blank?
    /\A[[:space:]]*\z/ === self
  end

  def original_blank_with_empty?
    empty? || (/\A[[:space:]]*\z/ === self)
  end

  def new_blank?
    empty? || !(/[[:^space:]]/ === self)
  end

end

def func string
  string.empty? || !(/[[:^space:]]/ === string)
end

GC.disable
Benchmark.ips do |x|
  x.report('new blank with empty while loop') do |t|
    i = 0
    while i < t
      func LONG_STRING
      i += 1
    end
  end

  x.report('patched string new blank with while loop') do |t|
    i = 0
    while i < t
      LONG_STRING.new_blank?
      i += 1
    end
  end
   x.compare!
end