We propose an efficient heuristic for the constraint-driven communication synthesis (CDCS) of on-chip communication networks. The complexity of the synthesis problems comes from the number of constraints that have to be considered. We propose to cluster constraints to reduce the number that needs to be considered by the optimization algorithm. Then a quadratic programming approach is used to solve the communication synthesis problem with the clustered constraints. We provide an analytical model that justifies our choice of the clustering cost function and we discuss a set of experiments showing the effectiveness of the overall approach with respect to the exact algorithm.