Device-to-device relaying can be applied to wireless multicasting to help reach a group of users in a resource efficient manner. Earlier work has focused on the resource efficiency of the relaying part, via subcluster partition and cluster head selection. We have extended that work to include the transmission part from a base station. We have reformulated the optimal subcluster partition algorithm and devised two sub-optimal heuristic algorithms to speed up the process of finding the cluster head and sharing the resources. The algorithms' performance have been assessed through simulations by comparing them to the optimal exhaustive search algorithm. The simple partition algorithm reduces the processing time by a factor of 4 while the resource efficiency stays optimal 90% of the time. The one-shot algorithm for deciding the transmission from the base station reduces the processing time by a factor of 20 while increasing the costs by less than 20% for 90% of the cases. This fast and efficient algorithm can be applied, for example, to safety messages multicasting in vehicular scenarios, for which delays need to be minimal.