Improving the application's startup time

In this recipe, we will show how to optimize widget set loading strategies. We will show how to speed up the starting of a Vaadin application by reducing the number of widgets that are initially downloaded from the server. A widget is a client-side implementation of a component, whic needs to be downloaded to the client browser.

First, we will create a simple UI class, which we are going to optimize:

public class MyVaadinUI extends UI {

    @Override
    protected void init(VaadinRequest request) {
        new WidgetSetOptimizer().extend(this);

        final VerticalLayout layout = new VerticalLayout();
        layout.setMargin(true);
        setContent(layout);
        
        Button button = new Button("Click Me");
        button.addClickListener(new Button.ClickListener() {
            public void buttonClick(ClickEvent event) {
                layout.addComponent(new Label("Thank you for clicking"));
            }
        });
        layout...