OpenStruct vs Struct vs Hash performance

open_struct_struct_hash.rb

require 'benchmark'
require 'ostruct'

REP = 1000000

User = Struct.new(:name, :age)

USER = "User".freeze
AGE = 21
HASH = {:name => USER, :age => AGE}.freeze

Benchmark.bm 20 do |x|
  x.report 'OpenStruct slow' do
    REP.times do |index|
       OpenStruct.new(:name => "User", :age => 21)
    end
  end

  x.report 'OpenStruct fast' do
    REP.times do |index|
       OpenStruct.new(HASH)
    end
  end

  x.report 'Struct slow' do
    REP.times do |index|
       User.new("User", 21)
    end
  end

  x.report 'Struct fast' do
    REP.times do |index|
       User.new(USER, AGE)
    end
  end

  x.report 'Hash slow' do
    REP.times do |index|
      {:name => 'User', :age => 21}
    end
  end

  x.report 'Hash fast' do
    REP.times do |index|
      {:name => USER, :age => AGE}
    end
  end
end

output

                           user     system      total        real
OpenStruct slow        8.150000   0.000000   8.150000 (  8.153797)
OpenStruct fast        7.980000   0.000000   7.980000 (  7.983929)
Struct slow            0.270000   0.000000   0.270000 (  0.268514)
Struct fast            0.200000   0.000000   0.200000 (  0.196950)
Hash slow              0.580000   0.000000   0.580000 (  0.584160)
Hash fast              0.460000   0.000000   0.460000 (  0.458502)

ruby 2.6.3 looks like hashes is faster than structs...

                           user     system      total        real
OpenStruct slow        0.760257   0.002922   0.763179 (  0.766513)
OpenStruct fast        0.597584   0.002368   0.599952 (  0.602767)
Struct slow            0.257806   0.003551   0.261357 (  0.265820)
Struct fast            0.220372   0.000379   0.220751 (  0.221160)
Hash slow              0.162665   0.001523   0.164188 (  0.166065)
Hash fast              0.128237   0.000906   0.129143 (  0.130054)

Ruby 3.0.2

                           user     system      total        real
OpenStruct slow        8.047000   0.000000   8.047000 (  8.061700)
OpenStruct fast        8.328000   0.016000   8.344000 (  8.341365)
Struct slow            0.157000   0.000000   0.157000 (  0.150189)
Struct fast            0.125000   0.000000   0.125000 (  0.125478)
Hash slow              0.093000   0.000000   0.093000 (  0.092687)
Hash fast              0.078000   0.000000   0.078000 (  0.077509)

Ruby 2.5.1

                           user     system      total        real
OpenStruct slow        0.796528   0.000174   0.796702 (  0.800543)
OpenStruct fast        0.579909   0.000018   0.579927 (  0.582189)
Struct slow            0.152336   0.000000   0.152336 (  0.152991)
Struct fast            0.132024   0.000000   0.132024 (  0.132460)
Hash slow              0.217203   0.000000   0.217203 (  0.217984)
Hash fast              0.205297   0.000000   0.205297 (  0.205531)

Ruby 3.2.2 arm64 macbook m1:

                           user     system      total        real
OpenStruct slow        5.198411   0.017713   5.216124 (  5.216191)
OpenStruct fast        5.079115   0.015835   5.094950 (  5.094971)
Struct slow            0.123186   0.000471   0.123657 (  0.123657)
Struct fast            0.103163   0.000209   0.103372 (  0.103370)
Hash slow              0.079912   0.000418   0.080330 (  0.080330)
Hash fast              0.070340   0.000254   0.070594 (  0.070595)

In case anyone is interested, I added Data to the benchmarks and also included having to access each object 10 times. This shows Struct and Data outperforming Hash if you include that they access the data faster.

https://gist.github.com/azrazalea-debtbook/ae2d46eb43e5fec421da739461484577

                           user     system      total        real
OpenStruct slow        7.414383   0.022696   7.437079 (  7.437549)
OpenStruct fast        7.375381   0.024232   7.399613 (  7.433433)
Struct slow            0.723688   0.002673   0.726361 (  0.726363)
Struct fast            0.698972   0.002602   0.701574 (  0.701566)
Hash slow              1.162884   0.004929   1.167813 (  1.204769)
Hash fast              1.114190   0.003281   1.117471 (  1.119175)
Data slow              0.825655   0.002959   0.828614 (  0.828610)
Data fast              0.803010   0.002993   0.806003 (  0.806002)