adds eager loading to avoid N+1 queries

app/controllers/debates_controller.rb

@@ -5,7 +5,7 @@ class DebatesController < ApplicationController
   respond_to :html, :js
 
   def index
-    @debates = Debate.search(params)
+    @debates = Debate.includes(:tags).search(params)
     set_debate_votes(@debates)
   end
 

app/controllers/welcome_controller.rb

@@ -2,7 +2,7 @@ class WelcomeController < ApplicationController
   skip_authorization_check
 
   def index
-    @featured_debates = Debate.limit(9)
+    @featured_debates = Debate.includes(:tags).limit(9)
     set_debate_votes(@featured_debates)
   end
 

app/models/comment.rb

@@ -11,6 +11,7 @@ class Comment < ActiveRecord::Base
   belongs_to :commentable, polymorphic: true
   belongs_to :user
 
+  default_scope { includes(:user) }
   scope :recent, -> { order(id: :desc) }
 
   def self.build(commentable, user, body)

app/models/user.rb

@@ -18,6 +18,7 @@ class User < ActiveRecord::Base
 
   accepts_nested_attributes_for :organization
 
+  default_scope { includes(:organization) }
   scope :administrators, -> { joins(:administrators) }
   scope :moderators,     -> { joins(:moderator) }
   scope :organizations,  -> { joins(:organization) }