Before revision:  Parallel maximal matching algorithms (adapted for switching) appear to have stricken the best such tradeoff. On one hand, they provide the following Quality of Service (QoS) guarantees: Using maximal matchings as crossbar schedules results in at least 50\% switch throughput and order-optimal (i.e., independent of the switch size N) average delay bounds for various traffic arrival processes.
After revision:  Parallel maximal matching algorithms (adapted for switching) appear to have stricken a sweet spot in this tradeoff, and prior work has shown the following performance guarantees. Using maximal matchings as crossbar schedules results in at least 50\% switch throughput and order-optimal (i.e., independent of the switch size N) average delay bounds for various traffic arrival processes.