Removing the scope-caching which happens on association proxies, because the query is already cached by the query cacher. For formalised proof see http://www.youtube.com/watch?v=wDefXLb-FDs

activerecord/lib/active_record/associations/collection_association.rb

@@ -21,14 +21,7 @@ module ActiveRecord
       attr_reader :proxy
 
       def initialize(owner, reflection)
-        # When scopes are created via method_missing on the proxy, they are stored so that
-        # any records fetched from the database are kept around for future use.
-        @scopes_cache = Hash.new do |hash, method|
-          hash[method] = { }
-        end
-
         super
-
         @proxy = CollectionProxy.new(self)
       end
 
@@ -74,7 +67,6 @@ module ActiveRecord
       def reset
         @loaded = false
         @target = []
-        @scopes_cache.clear
       end
 
       def select(select = nil)
@@ -327,10 +319,6 @@ module ActiveRecord
         end
       end
 
-      def cached_scope(method, args)
-        @scopes_cache[method][args] ||= scoped.readonly(nil).send(method, *args)
-      end
-
       def load_target
         if find_target?
           targets = []

activerecord/lib/active_record/associations/collection_proxy.rb

@@ -82,8 +82,6 @@ module ActiveRecord
             end
           end
 
-        elsif @association.klass.scopes[method]
-          @association.cached_scope(method, args)
         else
           scoped.readonly(nil).send(method, *args, &block)
         end

activerecord/test/cases/named_scope_test.rb

@@ -440,26 +440,31 @@ class NamedScopeTest < ActiveRecord::TestCase
     end
   end
 
+  # Note: these next two are kinda odd because they are essentially just testing that the
+  # query cache works as it should, but they are here for legacy reasons as they was previously
+  # a separate cache on association proxies, and these show that that is not necessary.
   def test_scopes_are_cached_on_associations
     post = posts(:welcome)
 
-    assert_equal post.comments.containing_the_letter_e.object_id, post.comments.containing_the_letter_e.object_id
-
-    post.comments.containing_the_letter_e.all # force load
-    assert_no_queries { post.comments.containing_the_letter_e.all }
+    Post.cache do
+      assert_queries(1) { post.comments.containing_the_letter_e.all }
+      assert_no_queries { post.comments.containing_the_letter_e.all }
+    end
   end
 
   def test_scopes_with_arguments_are_cached_on_associations
     post = posts(:welcome)
 
-    one = post.comments.limit_by(1).all
-    assert_equal 1, one.size
+    Post.cache do
+      one = assert_queries(1) { post.comments.limit_by(1).all }
+      assert_equal 1, one.size
 
-    two = post.comments.limit_by(2).all
-    assert_equal 2, two.size
+      two = assert_queries(1) { post.comments.limit_by(2).all }
+      assert_equal 2, two.size
 
-    assert_no_queries { post.comments.limit_by(1).all }
-    assert_no_queries { post.comments.limit_by(2).all }
+      assert_no_queries { post.comments.limit_by(1).all }
+      assert_no_queries { post.comments.limit_by(2).all }
+    end
   end
 
   def test_scopes_are_reset_on_association_reload