performance of method_missing vs fetch vs [] vs Hash#[]

performance of method_missing vs fetch vs [] vs Hash#[].rb

class U
  def self.compare(reports, n: 10)
    Benchmark.bm do |x|
      reports.each do |report|
        if report.is_a?(Proc)
          x.report { n.times { report.call } }
        else
          x.report(report.first) { n.times { report.last.call } }
        end
      end
    end
  end
end

user = SimpleHash[a: 1]
user2 = { a: 1 }
U.compare(
  [
    ['method_missing', -> { user.a }],
    ['fetch', -> { user.fetch(:a) }],
    ['[]', -> { user[:a] }],
    ['Hash#[]', -> { user2[:a] }]
  ], n: 1_000_000
)

#       user     system      total        real
# method_missing  1.397499   0.000694   1.398193 (  1.398357)
# fetch  0.534996   0.000523   0.535519 (  0.535599)
# []  0.416706   0.000161   0.416867 (  0.416923)
# Hash#[]  0.119884   0.000154   0.120038 (  0.120084)