Add gem "rubocop-performance"

.rubocop.yml

@@ -1,3 +1,5 @@
+require: rubocop-performance
+
 AllCops:
   TargetRubyVersion: 2.6
   DisplayCopNames: true

Gemfile

@@ -121,6 +121,10 @@ group :development, :test do
   # Aims to enforce the community-driven Ruby Style Guide.
   gem 'rubocop', '~> 0.67.2'
 
+  # A collection of RuboCop cops
+  # to check for performance optimizations in Ruby code.
+  gem 'rubocop-performance', '~> 1.1'
+
   # rspec-rails is a testing framework for Rails 3+
   gem 'rspec-rails', '~> 3.8'
 

Gemfile.lock

@@ -342,6 +342,8 @@ GEM
       rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 1.6)
+    rubocop-performance (1.1.0)
+      rubocop (>= 0.67.0)
     ruby-graphviz (1.2.4)
     ruby-progressbar (1.10.0)
     ruby_dep (1.5.0)
@@ -480,6 +482,7 @@ DEPENDENCIES
   rolify (~> 5.2)
   rspec-rails (~> 3.8)
   rubocop (~> 0.67.2)
+  rubocop-performance (~> 1.1)
   sass-rails (~> 5.0)
   selenium-webdriver (~> 3.14)
   sentry-raven