When vpackager builds a package for you, all it does it automate the steps you would have to take if you were doing it manually.
With that said, it is not intended to make your build times any shorter at all.
Some packages will take literally hours to build (For instance, try building KDE4 on a 1.5ghz CPU and let me know if you can do it within 3 hours
My point is, the time it takes to build a package only changes with the cpu speed or some flags parsed to the make process (which vpackages does not do because 7/10 times results in a failing build)
If vpackager has not hung on you, that means it's doing it's job, it's just the package taking forever to build.