Abstract : A detailed study of the performance of hierarchical radiosity is presented, which confirms that visibility computation is the most expensive operation. Based on the analysis of the algorithm's behavior, two improvements are suggested. Lazy evaluation of the top-level links suppresses most of the initial linking cost, and is consistent with a progressive refinement strategy. In addition, the reduction of the number of links for mutually visible areas is made possible by the use of an improved subdivision criterion. Results show that initial linking can be avoided and the number of links significantly reduced without noticeable image degradation, making useful images more quickly.