Actually I use Xfrogs Billboard trees in Bryce if I want o keep rendertimes low.I'd only use the tree lab if I wasn't using HDRI.

The first one was my first experiment and took about 20 minutes on default.with quality at 0 and intensity about 50 and HDRI at 100%.

The other was about 3 hours on regular render with the above settings for HDRI.Howevr as I say The pause render and save aspect of Bryce has saved my sanity as in this next one.It took about 6 hours in all.Mind with the reflection of the mirror and the glass and bottle I suppose I got off lightly.

You do know that you can do indoor scenes provided you click on the ceiling and or walls and in the material lab click on the options on the left(opposite the preview window) and click on cast shadows.This will allow light to pass into the building.