struct benchmark.rb

Bundler.setup(:default, :benchmarks)
Bundler.require

require 'benchmark'
require 'benchmark/ips'

ATTRS = ('a'..'z').to_a.map(&:to_sym).take(10)

class ManualStruct
  class_eval(<<-RUBY)
    def initialize(values)
      assert_known_attributes(values)
      #{ATTRS.map { |a| "@#{a}" }.join(', ')} = #{ATTRS.map { |a| "values[:#{a}]" }.join(', ')}
    end
  RUBY

  def assert_known_attributes(values)
    actual = values.keys
    unknown, missing = actual - ATTRS, ATTRS - actual

    fail if unknown.any? || missing.any?
  end
end

class ManualStructWithoutAssertion
  class_eval(<<-RUBY)
    def initialize(values)
      #{ATTRS.map { |a| "@#{a}" }.join(', ')} = #{ATTRS.map { |a| "values[:#{a}]" }.join(', ')}
    end
  RUBY
end


class KeywordStruct
  class_eval(<<-RUBY)
    def initialize(#{ATTRS.map { |a| "#{a}: " }.join(', ')})
      #{ATTRS.map { |a| "@#{a}" }.join(', ')} = #{ATTRS.join(', ')}
    end
  RUBY
end


values = Hash[*ATTRS.zip(ATTRS).flatten(1)]

Benchmark.ips do |x|
  x.report('manual') { ManualStruct.new(values) }
  x.report('manual without assert') { ManualStructWithoutAssertion.new(values) }
  x.report('keyword') { KeywordStruct.new(values) }
  x.compare!
end

__END__
Warming up --------------------------------------
              manual    14.345k i/100ms
manual without assert
                        50.236k i/100ms
             keyword    19.769k i/100ms
Calculating -------------------------------------
              manual    133.857k (± 8.2%) i/s -    674.215k in   5.073288s
manual without assert
                        643.960k (± 8.7%) i/s -      3.215M in   5.039824s
             keyword    187.779k (±13.2%) i/s -    929.143k in   5.048746s

Comparison:
manual without assert:   643959.9 i/s
             keyword:   187779.0 i/s - 3.43x slower
              manual:   133856.8 i/s - 4.81x slower