It would be a nice addition to org.apache.wicket.markup.html.debug.PageView to show how much time it took for a component to be fully initialized and the time to be rendered. This can be accomplished with a listener which implements IComponentInstantiationListener, IComponentInitializationListener, IComponentOnBeforeRenderListener, IComponentOnAfterRenderListener.
The initialization time measures from the call to Component.<init> (IComponentInstantiationListener), to the call Component.onInitialize() (IComponentInitializationListener) because there is no way to know when the component constructor ends.
Render time measures the time between IComponentOnBeforeRenderListener.onBeforeRender() and IComponentOnAfterRenderListener.onAfterRender().
The duration is collected in the meta data of the respective component.
The listener will be part of wicket-devutils sub-project.
Update: the instantiation time is not really useful in the way we can measure it so it wont be part of this feature request.