benchsort.rb

require 'benchmark/ips'
require 'faker'

def extract_tld(email)
  email.split('.'.freeze).last
end

emails = [].fill(0..1000) { Faker::Internet.email }

Benchmark.ips do |x|
  x.report("sort!") do
    emails.dup.sort { |a, b|  extract_tld(a) <=> extract_tld(b) }
  end

  x.report("map!.sort!.map!") do
    emails.dup
      .map { |x| [extract_tld(x), x] }
      .sort
      .map { |x| x[1] }
  end

  x.report("sort_by!")  do
    emails.dup.sort_by { |x| extract_tld(x) }
  end

  x.compare!
end