A slow client that participates in a reliable multicast session may reduce the speed of data transfer for other clients in the session. A multicast server can mitigate the effect of a slow client by identifying and disconnecting one or more clients that are slowing down the session, or by using other criteria to identify clients to be disconnected. The server may monitor the performance of clients in the session based on factors such as the rate at which each of the clients is able to receive data, the number or rate of packets lost by a client, the amount of time that a client has spent as the slowest client in the session, the identity of a particular client, etc. A client that has been identified for disconnection based on the server's detection efforts, or that has been identified by an administrator, may be disconnected.