Chris :

With the new GWT 2.0 (due to be released this year?), they have add a couple of great features. The one I’m most excited about from a users perspective is RunAsync (aka code splitting). To quickly recap, this feature will split a GWT application into multiple developer controlled (split points) downloaded files. We are reworking our internal GUI architecture and have decided to use the unreleased GWT version for development. Our largest application before compression (with obfuscation) is weighing in around 1.4MB. That’s pretty hefty for downloaded javascript files.

http://www.itsolut.com/chrismusings/2009/08/31/gwt-2-0-first-stab-at-runasync/