PERF: Remove ordering by username.

* Ordering by username results in a very expensive query
for very little upside UX wise.

app/controllers/directory_items_controller.rb

@@ -44,8 +44,7 @@ class DirectoryItemsController < ApplicationController
       end
     end
 
-    result = result.order('users.username')
-    result_count = result.dup.count
+    result_count = result.count
     result = result.limit(PAGE_SIZE).offset(PAGE_SIZE * page).to_a
 
     more_params = params.slice(:period, :order, :asc)

db/migrate/20161014171034_add_directory_items_indexes.rb

@@ -0,0 +1,11 @@
+class AddDirectoryItemsIndexes < ActiveRecord::Migration
+  def change
+    add_index :directory_items, :likes_received
+    add_index :directory_items, :likes_given
+    add_index :directory_items, :topics_entered
+    add_index :directory_items, :topic_count
+    add_index :directory_items, :post_count
+    add_index :directory_items, :posts_read
+    add_index :directory_items, :days_visited
+  end
+end