I noticed instancing isnt really instancing but creating more objects of the same kind.
Why I am saying that? Maybe I am wrong but:
If I create instances the created instances should not really slow down Bryce.
I mad a tree and created instances, maybe 50 of the and out them onto a mountain. After that Bryce slowed down substantially.
If there were real instances that should not have given me any real slow down with only 50 trees.
Here is the answer to your question. Even instances have virtual polygons which the wireframe view has to account for. All that complexity of the wireframe exceeds the expectations set forth 20 years ago when Bryce got its legs. Solution: Show as Box in the Attributes.
Show as Box simplifies the wireframe enough for navigation to come back closer to normal. For even faster navigation, make your source a Show as Box before you start painting it onto other surfaces. This way the instances are born already in Show as Box mode circumventing most of the slowdown.
Also with trees, even with Show as Box, its going to get slow. This is a particular problem with Bryce trees I have discovered, not sure the exact nature. But rest assured, they are true instances. The thing to remember is that the total number of polygons in a scene both real and virtual must be taken into account.
Have you read my short “intro” tutorial yet on the Instancing Lab? In that tutorial I explain the basic difference between mere replications and true Instances, and how and why it operates as it does.
This is an example of a render I made with the IL long ago, using Bryce trees even for the grass (leafless trees with lots of stems facing upward). While complex and natural looking beyond what is expected from most Bryce scene, the navigation is terribly slow. It takes 30 seconds for even simple changes to occur. We need 64 bit support badly. Fun Fun
Click thumbnail to see full-size image