This thesis examines the performance for multimedia distribution and information sharing of social-networking web sites, with a focus on user networks in Facebook. We used real user network data from Facebook together with a synthetic Facebook network in the performance-testing experiments. We tested performance for multimedia distribution and information sharing using three different types of overlay networks: Facebook; structured peer-to-peer (ring topology); and unstructured peer-to-peer (mesh topology). The experiments used Network Simulator 2 (Ns-2) to simulate the network topologies. The results show that structured Peer-to-Peer has the best performance in terms of information transfer, and Facebook has the best performance in regards to average throughput. This thesis shows the strengths and weaknesses of online social networking while sharing information and multimedia content.