The blackboard model is a versatile framework for implementing expert systems. In recent years the speed of blackboard access has been improved but the execution cycle, which manages knowledge source activation and execution, still needs substantial improvement. A method of condensing knowledge sources is presented, and it is shown how to efficiently activate and execute a class of blackboard application systems using the condensed representation. It is shown that the time complexity of the execution cycle of a condensed system is faster than that of the conventional approach by the ratio of the time required for blackboard retrievals to the time required for vector element retrievals. In practice, this ratio is approximately four order of magnitude.