1. A method comprising: recording into a script a plurality of script actions representative of a user's interactions with an application; replaying the script of recorded actions; receiving, by a processor-based machine, events that occur as a result of execution of the application, wherein the received events are dispatched by event sources during the replaying of the script; and using the received events to generate, by the processor-based machine, transactions for evaluating performance of the application when executed, wherein the transactions are generated in accordance with a set of transaction definitions, wherein each transaction definition in the set specifies actions which correspond to a start point and an end point of a transaction associated with execution of the application, and wherein the transaction definitions are provided separately from the script.