Optimize lib for large datasets

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

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

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

The issue names no files, tests, or entry points. Start by locating the parser entry points and configuration handling, then check whether notification support already exists. Done means parser notifications are controlled by enable_notifications, whose default is false, with behavior verified by the relevant tests.

Written by the indexing model from the issue text.