We had noticed that sometimes you can change scenes on a demanding model, and the animation is jerky. Other times the same scene change in the same model would be smooth. It was puzzling.
One of the developers noticed what was significant. It turns out that the feature that tries to keep up the frame rate is tied to the Orbit and Pan tools. Normally if you are using any other tool, the scene is not going to change its view, and so no reason to drop features in order to keep up the frame rate. If you are using Orbit or Pan, then the scene view will change, and the frame rate might drop.
In the case of scene transitions you do then have the case where Orbit or Pan are not selected, but the scene’s view is changing.
So, if you are changing scenes and the animation is not smooth, try selecting the Orbit or Pan tool first.