Still, I often run into clients who have Java compile times that run close to half an hour or more. By using good dependency management, and very fast compilers, I think this can be drastically reduced. But the problem still exists. Dynamically typed languages, however, have virtually zero compile time. There are no declarations to hunt down.
Compilation can occur while the code is being edited.
As projects get larger and larger, this ability to be instantaneously compiled will become ever more important. Finally, there is the issue of deployment. Thus, even a small change to a single class can cause large redeployment issues. In dynamically typed languages, redeployment problems are not eliminated, but they are vastly reduced. They are likely to become extremely important.