This is a little hard to explain, but appears pretty consistent:
I have a container COMP with three geometry COMPS inside it. Two of them contain animated geometry. The final one contains a single large background plane that sits behind the geometry and is textured with high resolution video. When I turn on the render and display flags of all three geometry COMPs and travel up the hierarchy, I achieve a framerate of approximately 20fps. If I save the file, and re-open it, I achieve a frame rate of less than 1fps. If I disable the render flag on the video and then save it and reopen it, my framerate goes back up to a normal speed. I can then re-enable the render flag on the video and maintain 20fps. However, if I save it like this, the problem reappears.
I’d love to see this example also if you wouldn’t mind sending it.