struct-vs-class-instanciation.rb

require 'benchmark'

class Foo
  attr_accessor :a
  def a
    @a = a
  end
end

class Bar < Struct.new(:b)
end

def build c
  c.new
end

n = 10_000_000
Benchmark.bmbm do |x|
  x.report("Class")  { n.times { build(Foo) } }
  x.report("Struct") { n.times { build(Bar) } }
end

__END__
Rehearsal ------------------------------------------
Class    1.760000   0.000000   1.760000 (  1.763450)
Struct   2.570000   0.000000   2.570000 (  2.574691)
--------------------------------- total: 4.330000sec

             user     system      total        real
Class    1.840000   0.000000   1.840000 (  1.845105)
Struct   2.720000   0.010000   2.730000 (  2.736802)