Java has jars and classes and dynamic calling. You don't compile everything into one big lump, nor you have to recompile millions of lines of code for one change in a file.

If Go wanted to compete on compile speed, then dynamic loading would be a better idea than having a simplistic compiler that compiles fast into one monolithic executable.

The main reason the Go compiler is fast, is because it is simple and doesn't do many passes and optimizations.

Which is like advertising the fact that your company makes a fast car, but forgetting to mention that it can only carry a driver if he weights 10kg.