Improve helpers performance

**Feature request**
It would be great to have monitoring for handlers.

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

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

Start by locating the handler implementation and existing configuration entry points; no files or tests are named in the issue. Clarify what handler monitoring should record, how it should be exposed, and how the default-disabled enable_monitoring option should be tested before defining completion.

Written by the indexing model from the issue text.