Symbolic techniques using BDDs and ADDs (binary and algebraic decision diagrams) are applied to the performance analysis of (asynchronous) timed systems. We model the system as a set of probabilistic finite state machines which is analyzed as a discrete time Markov chain. The stationary probability of all reach able states is obtained iteratively using ADDs. Average time separation of events is symbolically calculated to determine various performance metrics. Application to a FIFO and a differential equation solver chip demonstrates the feasibility of the technique.