Optimize handlers for large datasets

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

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

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

No files, tests, or entry points are named. Start by locating the configuration handling and helper notification paths, then clarify which notifications are required and how the `enable_notifications` option should affect them; done should include the documented default of `false` and coverage for the requested behavior.

Written by the indexing model from the issue text.