Dynamic traffic grooming in optical mesh networks is one of the most important and practical problems for designing wavelength-division-multiplexing networks. Most of the previous work solves this problem by applying the Dijsktra's algorithm on an auxiliary graph. Although those algorithms may give a good performance since they have a global view of the whole network, they are very time consuming and thus cannot be applied in large networks. Therefore, to the best of our knowledge, for the first time, we propose a heuristic algorithm to reduce the required computations by minimizing the size of the graph. We compare our algorithm with existing algorithms by extensive simulations in a typical 24-node mesh networks. The results demonstrate that our algorithm can significantly reduce the computational complexity, typically by a few tens times. Despite its simplification, our algorithm outperforms existing algorithms by large margins since it can easily avoid lightpaths that consume a large amount of network resources.