Refs -- Added a warning about performing queries in pre/post_init receivers.
Thanks Carlton Gibson the review.
@@ -106,6 +106,12 @@ Arguments sent with this signal:
``_state.db`` is ``None`` and cannot be used to check an ``instance``
database.
+.. warning::
+
+ For performance reasons, you shouldn't perform queries in receivers of
+ ``pre_init`` or ``post_init`` signals because they would be executed for
+ each instance returned during queryset iteration.
+
``pre_save``
------------
