Cheaper attribute reads and respond_to?. Add underscore-prefixed method aliased to the attribute name so it can be overridden but still called internally.

activerecord/lib/active_record/attribute_methods.rb

@@ -48,13 +48,13 @@ module ActiveRecord
     end
 
     def respond_to?(*args)
-      self.class.define_attribute_methods
+      self.class.define_attribute_methods unless self.class.attribute_methods_generated?
       super
     end
 
     protected
       def attribute_method?(attr_name)
-        attr_name == 'id' || attributes.include?(attr_name)
+        attr_name == 'id' || @attributes.include?(attr_name)
       end
   end
 end

activerecord/lib/active_record/attribute_methods/read.rb

@@ -70,13 +70,19 @@ module ActiveRecord
             if cache_attribute?(attr_name)
               access_code = "@attributes_cache['#{attr_name}'] ||= (#{access_code})"
             end
-            generated_attribute_methods.module_eval("def #{symbol}; #{access_code}; end", __FILE__, __LINE__)
+            generated_attribute_methods.module_eval("def _#{symbol}; #{access_code}; end; alias #{symbol} _#{symbol}", __FILE__, __LINE__)
           end
       end
 
       # Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
       # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
       def read_attribute(attr_name)
+        send "_#{attr_name}"
+      rescue NoMethodError
+        _read_attribute attr_name
+      end
+
+      def _read_attribute(attr_name)
         attr_name = attr_name.to_s
         attr_name = self.class.primary_key if attr_name == 'id'
         if !(value = @attributes[attr_name]).nil?
@@ -89,8 +95,6 @@ module ActiveRecord
           else
             value
           end
-        else
-          nil
         end
       end
 

activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb

@@ -19,12 +19,13 @@ module ActiveRecord
           def define_method_attribute(attr_name)
             if create_time_zone_conversion_attribute?(attr_name, columns_hash[attr_name])
               method_body, line = <<-EOV, __LINE__ + 1
-                def #{attr_name}(reload = false)
+                def _#{attr_name}(reload = false)
                   cached = @attributes_cache['#{attr_name}']
                   return cached if cached && !reload
-                  time = read_attribute('#{attr_name}')
+                  time = _read_attribute('#{attr_name}')
                   @attributes_cache['#{attr_name}'] = time.acts_like?(:time) ? time.in_time_zone : time
                 end
+                alias #{attr_name} _#{attr_name}
               EOV
               generated_attribute_methods.module_eval(method_body, __FILE__, line)
             else