Array#detect vs Hash#[]

array-detect-hash.rb

# This benchmark assumes we're consistently looking for the last
# item in the array.
#
# If you want to use a random number, use i = rand(1..20) in both
# reports.
require "benchmark"

n = 500_000

arr = (1..20).map { |i| { id: i } }
hsh = Hash[arr.map { |i| [i[:id], i] }]

Benchmark.bmbm do |x|
  x.report("Array#detect") do
    n.times do
      i = 20
      arr.detect { |item| item[:id] == i }
    end
  end

  x.report("Hash#[]") do
    n.times do
      i = 20
      hsh[i]
    end
  end
end

Results

                   user     system      total        real
Array#detect   0.683306   0.000014   0.683320 (  0.683338)
Hash#[]        0.023468   0.000000   0.023468 (  0.023469)