Overall the performances are quite good, except when deleting a CR item (i.e. an order line) which lasts forever (~80 sec).
Executing the function 'select content_item__delete' within a psql shell, I can observe the quick output of various 'raise notice' except the last call to 'acs_object__delete'.
I then added some 'raise notice' also to 'acs_object__delete' noticing that the time consuming operation is the last one, that deleting the row from acs_objects.
As far as I know there is only one trigger. deleting rows from acs_object_context_index, associated with the deletion of an acs object and I don't see any reason why this should last so much.