case-vs-hash-lookup.rb

require 'benchmark'

n = (ENV['N'] || 1_000_000).to_i

HASH = { foo: 1, bar: 2 }.freeze

Benchmark.bm(20) do |x|
  x.report("case") do
    n.times do
      case :baz
      when :foo then 1
      when :bar then 2
      end
    end
  end

  x.report("hash lookup") do
    n.times do
      HASH[:foo]
    end
  end

  x.report("hash fetch") do
    n.times do
      HASH.fetch(:foo)
    end
  end

  x.report("hash fetch w/ default") do
    n.times do
      HASH.fetch(:baz, 3)
    end
  end
end

results.txt

                           user     system      total        real
case                   0.060000   0.000000   0.060000 (  0.059396)
hash lookup            0.060000   0.000000   0.060000 (  0.060274)
hash fetch             0.090000   0.000000   0.090000 (  0.081596)
hash fetch w/ default  0.080000   0.000000   0.080000 (  0.086255)