Vaadin Bootstrap takes long to load


I implement a way to open my pages in a Dialog if needed. In that case the UI will be load by an URL in an embedded BrowserWindow:

Window window = new Window(title);
BrowserFrame browserFrame = new BrowserFrame(“Seite”, new ExternalResource(url));


Unfortunately the dialog takes a bit to open and I found out, that the vaadinBootstrap.js is loaded every time i open the dialog. Is there a way to tell the client to cache this file? Is it nesscesary to send it every time to the client. It takes 1s to 2s each time.

Thx for any hints.