EwProcess() represents the main loop of every Embedded Wizard GUI application. This main loop is responsible to provide all user inputs to the UI application, to start the processing of timers and signals, to take care for the update of the display and finally to start the garbage collection.
As you can imagine, the runtime for one loop (= one call of the function EwProcess()) dependes on the complexity of your GUI application, the user inputs, the amount of graphical objects that have to be redrawn.... And it depends on your target system (with or without hardware acceleration) and on the CPU speed...
With other words: It is not possible to predict the execution time. Of course, you can do measurements within your application.
Due to the fact that Embedded Wizard GUI applications are running in a cooperative manner, you can decide how much CPU time will be spent for the GUI thread and how much CPU time is necessary for other worker threads (e.g. to make some data processing).
I hope this helps...