Vaadin features

hi all,
i’m a newbie and i find Vaadin intersting. but can i run my webapp by vaadin in client-side and if user’s browser don’t support javascript switch it to server-side(as i know that vaadin apps run in server-side but GWT apps run in client-side user’s browser)? and can i write my web pages just in html and css(if i don’t use Java classes) and embeding vaadin in only parts in web page that i need AJAX features? for last question, how about performance (esp. speed) between Vaadin, GWT and JavaScript?
thanks

Nope. Vaadin needs JavaScript to run.

Sure.

This is quite complicated question - answer depends solely on your application. Please search the forums for discussions about performance.