PERF: fix N+1 on categories page

app/serializers/basic_category_serializer.rb

@@ -38,6 +38,6 @@ class BasicCategorySerializer < ApplicationSerializer
   end
 
   def notification_level
-    object.notification_level || CategoryUser.where(user: object.user, category: object).first.try(:notification_level)
+    object.notification_level
   end
 end

app/serializers/category_featured_users_serializer.rb

@@ -1,5 +0,0 @@
-class CategoryFeaturedUsersSerializer < CategorySerializer
-
-  has_many :featured_users, serializer: BasicUserSerializer, embed: :objects
-
-end

app/serializers/category_serializer.rb

@@ -71,4 +71,10 @@ class CategorySerializer < BasicCategorySerializer
     scope && scope.can_edit?(object)
   end
 
+  def notification_level
+   user = scope.user
+   object.notification_level ||
+     (user && CategoryUser.where(user: user, category: object).first.try(:notification_level))
+  end
+
 end