Performance of web pages and mobile device applications with multiple components rendered on a user device is dynamically speeded up, including dynamically measuring network communication latency, adjusting inter-boxcar intervals used to dispatch batches of action requests from the user device to a production server, and dispatching boxcarred requests to the server. Adjustments to the boxcar intervals are based on the dynamically measured network communication latency and a number of connections supported between the user device and the server. The measured network communication latency is calculated as dispatch-to-completed response time minus server processing time and the server processing time is received from the server for a boxcar of completed responses. The system adjusts according to feedback received, as a browser or mobile device changes network connections or the network conditions change, and adapting over time for a particular user. Inter-boxcar intervals are tunable and programmatically changeable, with values learned from experience.