**There is probably going to be now way around the render time to do something like foam and have it come out properly.  No matter how simple in geometry your foam object is,  there is always the material properties behind foam that will jack up your render times.  My two cents worth is if you want foam then you will have to pay for it with render time.  Render it at night or a little bit at a time when you do not need the computer.  Save it and come back and render some more later if you need to.

@ Stephen Ray:  You did a great job.  Gotta love those cigarette burns on the counter.**

Free men do not ask permission to bear arms!!