Ant script build time vs. Eclipse build time

Exporting a p开发者_如何转开发roject as a runnable jar takes approx 30sec to build, the (auto created) Ant script that does the same takes about 10 minutes to build.

What am I missing?

---

If you create things from Eclipse all components are already compiled whereas if you do this via a ant script everything must be compiled from the scratch so i would expect differences in compile/build time.