always describe from the viewpoint of the request and save queries

src/c3nav/mapdata/models/locations.py

@@ -177,7 +177,7 @@ class SpecificLocation(Location, models.Model):
 
     @property
     def subtitle(self):
-        groups = tuple(self.groups.all())
+        groups = tuple(self.groups.all() if 'group' in self._prefetched_objects_cache else ())
         return groups[0].title if groups else self.__class__._meta.verbose_name
 
     @cached_property