Optimize middleware for large datasets

**Description**
Currently handlers lacks proper import support.

**Proposed solution**
Add configurable import with sensible defaults.

**Priority**: Low/Medium

Start by locating the middleware and handlers responsible for imports, then read how current configuration and defaults are defined. Confirm the intended import behavior and identify the relevant verification path; done means handlers support configurable imports with sensible defaults.

Written by the indexing model from the issue text.