In this paper, we investigate issues of performance management in Digital Libraries. We defined a management architecture for measuring and monitoring the behavior of digital libraries as they operate, so that we can make performance conclusions using real life digital library load. Our architecture can be easily applied on any digital library system, introducing minimal overhead to digital library performance, and requiring minimal changes to the digital library code. We implemented this architecture over a testbed of Dienst servers using real data and workload. We defined the relevant parameters for investigating the performance of the servers and we made visualization tools to study the performance results. We also demonstrated how the performance results can be used by the digital library itself, to produce advanced unattended operations, like load balancing and dynamic timeout adaptation.