Question about number of objects and Celestia performance

[Starshipwright]

I know that the more objects Celestia has to create orbits for, the slower Celestia will run. Is that in reference to the number of objects in one solar system, or the number of objects total? Does Celestia create orbits for all objects all of the time, or only for objects in the active solar system?

Does the number of .ssc files have any effect on Celestia performance?
If the correct changes were made to the Celestia.cfg file, would splitting spacecraft.ssc into ISS.ssc, Mir.ssc and Hubble.ssc slow Celestia down?i

[selden]

The primary runtime slowdown is caused by the number of objects that are in the field of view and their visual interactions. A visually large foreground object obscuring many background objects (e.g. the Earth obscuring stars and galaxies) runs more slowly than when the same object occupies a small area on the screen, obscuring very few others.

The individual loading of textures and models of objects that become visible causes significant pauses, too.

When many objects are listed in catalogs that have been loaded, the tests to find which already-loaded objects are in the field of view can become significant.

Many tiny objects run much more slowly than using a single model to represent them all, especially when thousands are involved. That's why using an optimized data structure was important for the performance of the large galaxy database that's in the current version of Celestia.

I would not expect that splitting up catalog files would have any observable effect (so long as the total number of files is kept relatively small), although having to open more files always has more overhead than opening a single file at startup time.

[Starshipwright]

Thanks, I wanted clarification on that in order to decide what add-ons I would use.