Vaadin Applications Loading

Thank you for reading my question. I'm fairly new to Vaadin, so please bare with me. Following is the situation:

We plan to write a Vaadin front-end which contains a couple of hundred Vaadin portlets which are associated to a menu, which in turn will dynamically select the functions that need to be presented to the user. The UI will feature a set of menu options for the user to select, and based upon user's command, it will load the appropriate portlet to an adjacent Vaadin panel. Even though the intention is to have something like this, the question is whether this application will pre-load all the functions during initialization and take a long time to load? Should we follow a particular design pattern to avoid such undesirable delay in loading the front-end?