Very Cool. Proof:
Sorry for the inconvenience. After the server slowed down more and more today, I had a look inside the Apache error log and realized that the MaxClient limit was exceeded. A quick look revealed that I had not changed the default value from 20 to something much higher and that the server was idle all the time. And since Amberjack appeared on Ajaxian yesterday and was seen as the second link on the del.icio.us homepage, its getting quite crowdy!
Anyway, it should work like a charm now. Let me know if you experience something else 🙂