Watch what you do at startup !
Don’t call setStyle() if you can avoid it, it’s one of the most expensive calls in the framework since it can trigger reloading styles in every component on the display list. If you have to call setStyle(), do it in the INITIALIZE event handler instead of the CREATION_COMPLETE handler. Use deferred instantiation when possible (leave creationPolicy=”auto”). Avoid unneccessary nesting of containers.