Improve controllers performance

**Feature request**
It would be great to have notifications for models.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_notifications` with default `false`.

Start by locating the configuration handling and the controller or model lifecycle where notifications would be triggered. Determine what notification events and delivery behavior are expected, then add the disabled-by-default enable_notifications option and tests that verify the configured behavior.

Written by the indexing model from the issue text.