In the case of serialization libraries,unless you are validating as part of your (de)serialization, I'd recommend avoiding schema-driven serialization libraries. These Kim-like libraries, such as Marshmallow, introduce quite a bit of overhead. If validation isn't required and performance matters, I recommend choosing a lighter-weight serialization/marshalling alternative, such as that provided by asphalt-serialization: https://github.com/asphalt-framework/asphalt-serialization

Asphalt-serialization supports cbor, msgpack, json, ... and is easy to wire up

This recommendation is based on my own experience using Marshmallow for Yosai, analyzing its performance and then refactoring to a ported version of asphalt-serialization.