The PageAsyncTask.ExecuteInParallel property is set in the constructor. When multiple tasks are registered in a page and the PageAsyncTask.ExecuteInParallel property is set to true, then those tasks are processed concurrently. However, if the PageAsyncTask.ExecuteInParallel property is set to false, then those tasks are processed sequentially. For example, if a page contained two asynchronous tasks that each took 5 seconds to complete and PageAsyncTask.ExecuteInParallel is set to true, both tasks will complete in 5 seconds. If PageAsyncTask.ExecuteInParallel is set to false for these same two tasks, then the first task will complete in 5 seconds and the second task will complete 5 seconds after the completion of the first task.