I have been using rendering type short cuts for a few years in Second Life for a few years now. I did not always know they were called rendering types, I just knew how to use them, or at least the short cuts. When I first started using them it was during my vampire role-playing days. These were helpful when I needed to fight using HUDs and weapons because my pc at the time couldn't handle the graphics moving around and rendering so much. I would "turn off" as much rendering as possible/needed, then fight. I like to think I did fairly well, from what other people have said, but that was years ago.
Sometimes these shortcuts are helpful for shopping or getting around a sim as well. Just remember to turn them back on, or things will look off. I have left one off one day, logged back in and was confused on why things weren't "loading" properly. It is a good idea to try everyone and see how it can be useful for you, either now or in the future. These tools can also be a lot of fun for interesting photography or settings. These shortcuts can also be reached under the Advance Menu under Rendering Types. Have fun, and tell me how you use, or might use these tools.
For those that may not be able to see the photo there is a list below of the short cuts: