Autonomous agents have proved to be a very adequate paradigm to construct platforms that support mobile computing. However, existing platforms, in the form of middleware or frameworks, have important shortcomings that should be addressed. Consider power consumption in JADE/LEAP, one of the most accepted agent frameworks for devices like PDAs and mobile phones. We describe the design and implementation of a real multicast communication mechanism to support internal group communications in JADE/LEAP, which obviously permits a reduction in the amount of real messages between agents, resulting in power savings. The importance of this work is that we prove our proposal is both effective, because it does not affects the framework performance, and transparent to the application, because the framework?s API requires no modifications. Moreover, during the testing of our proposal we found a problem with JADE/LEAP?s internal cache. We present a quantitative analysis to assess this problem?s impact on performance.