Programming practises for QT- load balancing/performance

Hi all,

Let's say I am building a large QT application (I think there are at least 5 distinct modules, with each module having 2 to 3 property browser and a toolbar, plus about three or four more dialog boxes), what is the best way to go about achieving good performance?

1. Create and initialise all modules (each is basically a QWidget which I add to a tab) at start up

OR

2. Only create the widget the module is invoked, and destroy it (de-reference it?) when the module is closed

Is there any need to do such things, or is QT handling this under the hood?

Creating and deleting stuff takes time, so if you can keep them, that would increase speed, but at the cost of memory. It is the classical computer science trade-off - memory vs cpu cycles.