Ruby benchmark: Array#uniq vs Set#to_a

bench.rb

#!/usr/bin/env ruby

require "benchmark/ips"
require "set"

INPUT = 100.times.map { "my-test-string" }.freeze

Benchmark.ips do |x|
  x.report("Array#uniq") { INPUT.uniq }
  x.report("Set#to_a") { Set.new(INPUT).to_a }
  x.compare!
end

__END__

# I've omitted frozen string literal because the app under testing doesn't use it AND `Set#initialize` freezes strings.
# I wanted to reproduce the cost of freezing the strings in a scenario where they aren't frozen by default.
# 
# > When a string is to be stored, a frozen copy of the string is stored instead unless the original string is already frozen.
# See: https://ruby-doc.org/stdlib/libdoc/set/rdoc/Set.html

Result:

  Warming up --------------------------------------
            Array#uniq    13.739k i/100ms
              Set#to_a     5.406k i/100ms
  Calculating -------------------------------------
            Array#uniq    146.702k (± 3.2%) i/s -    741.906k in   5.063030s
              Set#to_a     55.793k (± 4.0%) i/s -    281.112k in   5.047296s

  Comparison:
            Array#uniq:   146702.0 i/s
              Set#to_a:    55793.0 i/s - 2.63x  slower
Ruby:

    ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-darwin16]

Hardware:

    Hardware Overview:

      Model Name: MacBook Pro
      Model Identifier: MacBookPro12,1
      Processor Name: Intel Core i7
      Processor Speed: 3,1 GHz
      Number of Processors: 1
      Total Number of Cores: 2
      L2 Cache (per Core): 256 KB
      L3 Cache: 4 MB
      Memory: 16 GB
      Boot ROM Version: 184.0.0.0.0
      SMC Version (system): 2.28f7

Software:

    System Software Overview:

      System Version: macOS 10.12.6 (16G2016)
      Kernel Version: Darwin 16.7.0
      Time since boot: 16 days 22:33