This document describes systems, methods, devices, and other techniques for monitoring the performance of activities executed at a computing device. In some implementations, a computing device receives a user input to invoke performance of an activity by the computing device. Multiple portions of computer code associated with the activity can be identified. For each portion of computer code, (i) the respective portion of computer code can be executed, and (ii) data can be recorded about the executing of the respective portion of computer code that indicates a time duration of the executing of the respective portion of computer code. A total time to completion of the activity can be provided based at least in part on aggregating the recorded data about the executing of the multiple portions of computer code.