Consider deprecating old config API

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

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

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

The issue names no files, tests, or entry points. Start by locating the existing configuration API and helper execution path, then determine how caching should integrate with them. Done means an agreed design for helper caching and a new enable_caching option whose default is false.

Written by the indexing model from the issue text.