Welcome to the forum, Marc. 

Now, the quality of the preview renderer isn't really comparable to Firefly. You won't get good lights, reflection, refraction or reasonable shaders. I would use Firefly for the final render for any real animation, although I would make sure that the render settings are as low as possible, for the quality I want to archive.

If time is really an issue, I would try not to use ray tracing. This would mean no IDL and no AO, no real reflections too (but reflection maps are possible), so lighting a scene can be problematic, but you will have very short render times with a much higher quality than with the preview renderer. If you are interested, here is a nice presentation from Pixar in which they explain the use of Ray Tracing in the "Cars" movie - Pixar did not use Ray Tracing in earlier movies.

Movies have long render times, if you want quality. If possible, use a couple of computers for rendering, all pro versions can do that. 

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

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