1. A computing apparatus comprising: one or more computer readable storage media; and an application comprising interpreted program instructions stored on the one or more computer readable storage media and executable on a single thread, the interpreted program instructions comprising: a plurality of task modules for loading an email folder in a user interface to the application, each of which when executed on the single thread by a processing system, directs the processing system to return control to a scheduler module upon completing; and the scheduler module, wherein the scheduler module, when executed on the single thread by the processing system upon control returning from any of the plurality of task modules directs the processing system to at least: determine whether user interaction has occurred in a user interface to the application since last having granted control to any of the plurality of task modules; if the user interaction occurred and pertained to one or more emails in the email folder being loaded, then grant control to a task module out of order with respect to a programmed order of the plurality of task modules; and if the user interaction did not occur, then grant control to a next task module in the programmed order of the plurality of task modules.