1. A method, comprising: calculating a first application performance signature for an application at an application server; calculating a second application performance signature for the application at the application server after providing an update to the application, wherein the first and second application performance signatures are computed from a service time for transaction requests from a client computer; processing the first and second application performance signatures on a processor-based machine to compare the first and second application performance signatures to determine whether a change in transaction performance at the application server results from the update; and providing results of the change to a user.