Cache multiple scene content when rendering animation

In some renders, people do you'll have more than 1 scene you're working with. One might be a detailed Cycles render for the foreground, and the second less detailed EEVEE render so the background can be rendered faster, then combining them both in the compositor.

While this is faster for single frame renders, this doesn't help in the case of animations because for whatever reason when the Blender Renderer starts a new render it loses the cache of what it was previously rendered. I don't believe there is a workaround for this. For animations, it genuinely becomes faster to combine your two scenes into one, because if you don't then each render will independently render each frame, loading it's resources each time.

There is a second option; the ability to order how scenes are rendered. Being able to tell blender to render these sets of frames out first, storing them in a folder as images, avoiding having to reload the resources for every frame, then later using the previously rendered frames from the folder to be added into the final compositing.

Either option, however, I reckon can greatly boost the speed of renders. Being able to set backgrounds to use eevee or Fast GI, have a larger noise threshold or a faster less clean form of denoising would be amazing.

Thanks for listening to my Ted talk?

Following video is just of a old project rendering where I had the stated issue. Was made for blender 2.8, didn't really optimise it for blender 3.0