A monitoring system monitors processing of incoming messages and logs data related to performance of an application that processes the messages. The monitoring system temporarily associates reusable identifiers with the messages and logs data upon each message traversing different points in the application. Each of the identifiers is sized such that the storage space necessary to store the identifier is less than the storage space necessary to store an identifier sized to uniquely identify all of the plurality of messages, and the identifiers and the logged data are configured to minimize a performance penalty of monitoring the application. The monitoring system parses the data, e.g., during post-processing, to determine, from a plurality of data entries that refers to the same identifier, a subset of the data entries where the same identifier was associated with the same message.