1. A method of scheduling execution of a plurality of tasks by a processor, the processor having a processor memory, the processor being arranged to load into the processor memory, during execution of a current task, data for a task that is scheduled for execution after the processor has completed the current task, the method comprising the steps of: scheduling a next task for execution by the processor after the processor has completed a current task; determining whether there is a high priority task to be executed by the processor; if there is a high priority task to be executed by the processor: determining whether the processor has begun loading the data for the next task into the processor memory; and if the processor has not begun loading the data for the next task into the processor memory, scheduling the high priority task, instead of the next task, for execution by the processor after the processor has completed the current task.