Attached Link: http://www.keindesign.de/stefan/poser/renderer.html

*I wonder how high the bucket size can be cranked?* You can crank it up until you don't have any RAM left, in which case MacOS X will start using swap space on the hard drive as virtual RAM and your rendering will become terribly slow. If you turn it up too much, it can also happen that FireFly aborts the render process because the system denies its requests for memory. Note that the bucket size does not affect the image quality, what it does is speed up rendering at the expense of using more RAM. The default of 32 is probably set for systems with 256MB RAM - if you have a GB RAM or so, use at least 64 or more. I have 640MB RAM and use a bucket size of 64 most of the time, if not 96. As for the other rendering settings, I put a brief explanation of them with some example images on my web site.