bench_hash.rb

require 'benchmark/ips'
require 'securerandom'
require 'digest'

NUMBER = 10_000

id_array = Array.new(NUMBER) { SecureRandom.uuid }.freeze

def slow(array)
  Digest::MD5.hexdigest(array.join('/'))
end

def fast(array)
  array.hash
end

Benchmark.ips do |x|
  x.report("MD5#hexdigest")       { slow(id_array) }
  x.report("Array#hash") { fast(id_array) }
  x.compare!
end

results

Warming up --------------------------------------
       MD5#hexdigest    68.000  i/100ms
          Array#hash    51.000  i/100ms
Calculating -------------------------------------
       MD5#hexdigest    699.184  (± 3.4%) i/s -      3.536k in   5.063895s
          Array#hash    520.148  (± 1.9%) i/s -      2.601k in   5.002243s

Comparison:
       MD5#hexdigest:      699.2 i/s
          Array#hash:      520.1 i/s - 1.34x  slower