Improve handlers performance

**Description**
Currently controllers lacks proper serialization support.

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

**Priority**: Low/Medium

Start by locating the controllers and handler code responsible for serialization, then inspect how responses are currently produced. Done means serialization is configurable and has sensible defaults, with the relevant behavior covered by the project's existing checks or tests.

Written by the indexing model from the issue text.