http://www.daz3d.com/forums/viewthread/15981/#234284

Bryce has an issue with memory(history buffer) , it keeps saving your work for the Undo option and in the end can assimilate all the RAM, Horo recommended to save your work in a scene file sometimes then close Bryce and reopen and load your scene.

Also importing obj in Bryce is a hard task for Bryce, don't forget to click "E" from the object to smooth its polygons ,this might help, specialy if its not a highly detailed obj and the camera is not focused on it.

Also remove parts of an object if you render only the shell of that obj, example: remove the cockpit from an airplane (if it has interior parts) if you render only the airplane.Same goes for houses, if you render a house from outside , you don't need interior parts, or a backside wall.I guess you know how to select parts of an object and remove them ? hold CTRL and click on object.Then hit Delete to remove unwanted/unseen parts.Before to remove unwanted parts make sure you have saved camera or the view angle.To save a view angle just click on the small green lines bellow the nanoview.To remove them, hold ALT and click again to delete the saved view angle.

Remember ,you render what you see, but bryce fills memory with every detail even from interior objects.Keeping in scene only the obj which are on camera angle for rendering prevents lagging too while working with complex scenes.

I see your castle scene and if this is the angle you'll render , you can try to remove the wall from the right side because i bet that will be invisible to final render.I don't recommend to hide it by clicking "A" (attributes) because im not sure if bryce will remove it completely from RAM.

Oh, and visit often Bryce forum too, is very active and you can find useful tips and tricks . 

Edited by cris333 on 02/01/13 02:19 AM.