There's lots and lots of cool new stuff in GWT 1.4, so it's hard to know where to start. How about application performance?! This release includes several breakthroughs that make your compiled GWT code significantly smaller and faster. Many users are reporting that after a simple recompile with 1.4, their applications are up to 30% smaller and 20%-50% faster. And startup time in particular is now highly optimized thanks to a new bootstrapping technique and the availability of image bundles. To see the new hotness in action, try visiting the new-and-improved Mail sample a few times. It's darn fast the very first time you visit it, but subsequent visits are insanely fast. That's because, in addition to a fast initial startup, GWT code uses a clever caching technique to prevent applications from making unnecessary HTTP requests. As Joel Webber (Tech Lead of GWT Core Libraries) would say, "The fastest HTTP requests are those that do not, in fact, occur."