In Drupal 7 we were able to use field_attach_update($entity_type, $entity) to update fields without having the need to update the whole node. $node->save() is very heavy and calls many hooks in between.
With the coming of Drupal 8, field_attach_update was deprecated. Is there an alternative to it, and what is it if yes?
In my case I'm updating two image fields programatically and don't want to call $node->save in order to not trigger all the other hooks.
There is no alternative, saving an entity is the only supported API.
Saving will only update the configurable field tables if it detects a change, and we plan to implement similar logic for the base tables as well.
But the hooks are still called and there is no supported way to prevent that.
email_send() function when the node is saved but would like to avoid that when the node is updated programatically. Also in my case, I generate programatically 2 fields based on the form values and would like to persist them without having to save the node again. Updating the db directly is not safe.