Limited user queries when appropriate

Fixes #48.

@@ -91,7 +91,8 @@ class BaseCommentNode(template.Node):
             qs = qs.filter(is_public=True)
         if getattr(settings, 'COMMENTS_HIDE_REMOVED', True) and 'is_removed' in field_names:
             qs = qs.filter(is_removed=False)
-
+        if 'user' in field_names:
+            qs = qs.select_related('user')
         return qs
 
     def get_target_ctype_pk(self, context):

@@ -154,11 +154,11 @@ class CommentTemplateTagTests(CommentTestCase):
 
         # Clear CT cache
         ContentType.objects.clear_cache()
-        with self.assertNumQueries(4):
+        with self.assertNumQueries(3):
             self.testRenderCommentListFromObject()
 
         # CT's should be cached
-        with self.assertNumQueries(3):
+        with self.assertNumQueries(2):
             self.testRenderCommentListFromObject()
 
         # {% get_comment_list %} --------------------