The feedrate parameters and overall machining time will be defined by the following:
1) Overall size
2) Relief height
4) Tool diameter
5) Relief complexity
6) Stock Material
If you're machining out of wood then it may be a valid tradeoff to reduce the machining time with a larger stepover but spend a little time with some sandpaper to clean it up. I know that this has become my preferred way to work on a Sherline where the machine can hiccup after a very long machining time.
If you can fill in the other parameters then I'm sure others can suggest some starting points for you.