A system for monitoring the post-deployment performance of a web-based or other transactional server is disclosed. The monitoring system includes an agent component that monitors the performance of the transactional server as seen from one or more geographic locations and reports the performance data to a reports server and/or centralized database. The performance data may include, for example, transaction response times, server response times, network response times and measured segment delays along network paths. Using the reported performance data, the system provides a breakdown of time involved in completion of a transaction into multiple time components, including a network time and a server time. Users view the transaction breakdown data via a series of customizable reports, which assist the user in determining whether the source of the performance problem. Additional features permit the source to be identified with further granularity.