Add benchmark specs

spec/benchmark_spec.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+describe "Performance testing" do
+
+  let(:disposable_domain) { ValidEmail2.disposable_emails.first }
+
+  it "lookup timing" do
+    # preload disposable emails
+    list    = ValidEmail2.disposable_emails
+    address = ValidEmail2::Address.new("test@example.com")
+
+    expect { address.send(:domain_is_in?, list) }.to perform_under(0.0001).sample(10).times
+  end
+
+end

spec/spec_helper.rb

@@ -1,6 +1,15 @@
 $:.unshift File.expand_path("../lib",__FILE__)
 require "valid_email2"
 
+# Include and configure  benchmark
+require 'rspec-benchmark'
+RSpec.configure do |config|
+  config.include RSpec::Benchmark::Matchers
+end
+RSpec::Benchmark.configure do |config|
+  config.disable_gc = true
+end
+
 class TestModel
   include ActiveModel::Validations
 

valid_email2.gemspec

@@ -23,6 +23,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler", "~> 2.0"
   spec.add_development_dependency "rake", "~> 12.3.3"
   spec.add_development_dependency "rspec", "~> 3.5.0"
+  spec.add_development_dependency "rspec-benchmark", "~> 0.6"
   spec.add_development_dependency "pry"
   spec.add_runtime_dependency "mail", "~> 2.5"
   spec.add_runtime_dependency "activemodel", ">= 3.2"