Add rate limiting for filtering

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

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

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

The issue does not name files, tests, or an entry point, and its title mentions rate limiting while the body requests helper imports and an enable_import option. First locate the configuration handling and filtering or helper-import implementation, then clarify which behavior is intended; done should include the agreed configuration behavior and tests for it.

Written by the indexing model from the issue text.