Just wanted to drop a hint. I recently had to render one of my images to 360 dpi and 8"x 10" size. I did it first using Bryce 4 as it renders quicker by a large factor on my machine. Or so I thought. It seems this isn't true when using render to disk ops. In version 4 it took 28hrs and change with over 5 QUADRILLION OPERATIONS! (yes QUADrillion). I then used Bryce 5 and it took a little more than 4 hrs with ops in the trillions as usual. The moral of the story is Use Bryce 5 for large renders and render to DISK! Bryce 4 still beats ver 5 when rendering to screen and using "export image" to save. The rendering settings were 3x antialias and grouped optimization (agressive) with no advanced Bryce 5 rendering options set. Hope this works for you too. It saved me over 20 hrs!

3x antialias?

that's what I was wondering, but didn't want to look stupid by asking.... thanks for taking on that responsibility, A.S. ;)

Bryce has never had oversampling of the Anti-Alias feature(2x, 3x, etc) Anyway, there HAD to be a setting that was different in the two renders. You can't do the same exact render settings in both 4 & 5 and end up with 4 having Quadrillions and 5 only having trillions, it's simply impossible. I'm sure what happened is in the Bryce 4 render your settings were on "AntiAliasing Fine Art(Slow)", which will make a render go from trillions to quadrillions, no problem. BUT, you probably didn't save the Bryce 4 scene with the AA set to Fine, so when you brought in into Bryce 5, it rendered it on "Regular (Normal AntiAliasing)", thus getting done so fast and with less Intersect Attempts. I tried what you said with a scene of mine, no difference in the render results, other than a little more time in Bryce 5. (19 sec. vs. 18sec.) I then took the same scene back in Bryce 4 and set it to "AntiAliasing Fine Art(Slow)". It went from a speed of 18 seconds to 2min. 9sec. and went from 6.81 million to 4.82 billion. AS

One q though, is render to disk faster than render on screen?

Somewhat, yes. Your video card and cpu do not have to process the information of constantly updating your monitor screen with the ongoing render. This can get more apparant in PC's that have slower video cards. And, even more apparant if while you are rendering on your screen, you are also flipping through other windows, especially anything with graphics. Still, not a giant difference in time. I've noticed an average of an extra 3 seconds added on for every mintue of rendering on screen. Instead of a 60 minute render, it would be around 63 minutes. But, then again, I have a Ge-Force 4 64Mb video card.

Maybe 3x antialias is 9 rays per pixel? a square of 3 rays wide and high makes up for one pixel that way.

"with no advanced Bryce 5 rendering options set." You have to use advanced render settings to use the rays per pixel. AS