Consider deprecating old api API

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

**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 handler entry points. Start by locating handler configuration and existing cache-related code, then clarify whether the requested caching work or the title's API deprecation is in scope. Done should include a documented enable_caching default and tests covering disabled and enabled behavior.

Written by the indexing model from the issue text.