Collaborative virtual environments (CVEs) such as massive multi-user 3D games and military training environments can place strict requirements on network when participating users are sharing the 3D virtual environment through mobile devices in an ad-hoc network. This paper presents an optimization mechanism for Gnutella network to better meet the mobility and the network requirements of collaborative virtual environments (CVEs). With the rapidly increasing use of mobile personal devices, we are facing new challenges and opportunities for making efficient Mobile Collaborative Virtual Environments (MCVEs) applications based on Gnutella network. The proposed work comprises an enhancement of the Gnutella network through an efficient overlay formation protocol, and a novel caching optimization technique implemented in specific nodes selected through a Gnutella Ultrapeer System (GUS) mechanism. The resulting approach should overcome several problems including flooding and the limited capacity of mobile devices. In order to evaluate our designed protocols, we run the system over several ad-hoc routing protocols, simulation results shows that each ad-hoc routing protocol performs well only under specific simulation scenarios.