When an object has lots of inverse relations (hundreds or more), the relations tab in the backend(admin2 siteaccess) stops responding. the DB returns a timeout while fetching all the related objects.

this behavior depends on how fast the db server can fetch all the objects. can break with just a few hundred or need more than a thousand objects.

Steps to reproduce

-create an object X with the "object relations" attribute.
-create around 1000 objects and relate them to X.
-in content tab in the backend, click on the object, then on the relations tab
-the page will hang waiting for all the related objects to show.