I think best advice is to buy a book about zen meditation. Patience is the best advice for things like that. Oh, another advice. Try Radiosity and you will happily return to global illumination. It simply is in the nature of these methods that they are very VERY calculation intense. Especially with such high settings of ultra. So if you want to use them and you have reflections and/or transparency in the image you have to wait. And wait. And wait... It is the same with all programs - as i said, it is in the nature of the methods. Maximum cpu use for these. It is no surprise that some Cinema 4D scenes are used for benchmark to compare cpus these days. However. What is the advice really? Not much really. Think about what method you want to use, especially when you have big reflecting areas and/or transparent ones in your image. Sometimes images can even look better with standard atmospheres used. I had that in several cases.

One day your ship comes in - but you're at the airport.