As your JavaScript projects get more and more complex, loading all of your Dojo javascript files can really slow down your load time. All those dojo.require calls add up in a hurry. The Dojo Build System can be a huge help in speeding up the load time and general performance of your apps. For example, a build that I ran on a recent project took the number of JavaScript requests on page load from 53 down to 5. The css requests went from 16 down to 4. This ended up cutting the load time in half! Other nice features include stripping out all of the console calls, minifying your JavaScript and interning all of your widget templates.