Switch-trees are peer-to-peer algorithms for building and improving end-host multicast trees. Nodes switch parents to reduce tree cost or lower source-member latency. A node switches parents by disconnecting from its parent and reconnecting to a new parent. If the new parent is well chosen, the performance of the tree is improved overall. We look at the performance of switch-trees using the following metrics: cost, latency, link stress and number of switches. Simulations show switch-tree algorithms can build trees of hundreds of nodes at less than twice the optimal cost. In addition, we describe our implementation of a switch-tree protocol. Experiments show that our protocol builds low-cost trees in practice.