At the moment all field table properties are decoded when decode functionality is invoked. For use cases when only some of the field table properties are queried, the decoding functionality can be changed to stop decoding on getting the requested property. Potentially, such approach can improve the performance of routing transient messages when destinations are bound to the routing exchange using selector filters. As filter expression contains only some properties, the decoding of message headers can be stopped on getting all fields specified in selector expression.
The idea is illustrated by Rob Godfrey on QPID-8238