J2EE-containers can take a while to start indeed (for large projects), but in most cases they can be tuned to restart in less than 10sec - at least during devel

J2EE-containers can take a while to start indeed (for large projects), but in most cases they can be tuned to restart in less than 10sec - at least during development. Using GWT you don't "write Javascript in Java", the java-code is written in java and then compiled to optimized, cross-browser, javascript. Compile-times can be quite long - but again, during development you will use the hosted-mode (or even the new super-dev-mode) version, which compiles on the fly. Full java-to-javascript compilation is typically only needed when new versions are deployed to stage/prod.