https://github.com/Shopify/liquid/pull/499

which_date_comparison_is_faster.rb

require 'benchmark/ips'

def alter(obj)
  return obj if obj.respond_to?(:strftime)

  obj.downcase! if obj.is_a?(String)

  case obj
    when 'now'.freeze, 'today'.freeze
      Time.now
    when /\A\d+\z/, Integer
      Time.at(obj.to_i)
    when String
      Time.parse(obj)
    else
      nil
    end
rescue ArgumentError
  nil
end

def neuer(obj)
  return obj if obj.respond_to?(:strftime)

  case obj
    when /\A(?:now|today)\z/i
      Time.now
    when /\A\d+\z/, Integer
      Time.at(obj.to_i)
    when String
      Time.parse(obj)
    else
      nil
    end
rescue ArgumentError
  nil
end

[ 'Now', 'Today', 'now', 'today', '1418842869', nil ].each do |arg|
  Benchmark.ips do |x|
    x.report("old #{arg.inspect}") { alter(arg) }
    x.report("new #{arg.inspect}") { neuer(arg) }

    x.compare!
  end
end