Yep, that's normal. I've had files with MANY millions of polygons, with file sizes reaching half a gig. Ask Ornlu what his biggest file was, but be prepared to catch your jaw before it hits the floor.

Keep these in mind when the saving/render times reach epic proportions:

1. If you can't see it, forget about it. (ie. If it is not going to be visible in the final render, why waste time and resources modelling it?)
2. Try modelling your scene in sections, saving each section to its own BR5 file. When you are ready for the final render, merge the files together.
3. Volumetrics, transparent and reflective materials increase render times exponentially. Use them sparingly.
4. Poser models are murder when it comes to poly count. Try using 2D pic objects instead. Do a Gallery searh for "roobol" to see what I mean.

Sweet castle by the way! I look forward to seeing where you go with this. :)

-Jay