Method for performing a software process, controller and lithographic apparatus

A method for performing a software process, such as a real time software process, is disclosed, the process having a plurality of tasks, the method including starting a task of the plurality of tasks of the process, monitoring a progress of the started task, comparing the progress with a desired progress, if the progress does not meet the desired progress, skipping at least a part of a task of the plurality of tasks, and performing the process making use of an outcome of the tasks which have been completed. The monitoring of the progress may be performed upon completion of the task or at a predetermined moment in time.