You need to split up your comp into shots. There is a display limit, and it's a very bad idea to have one comp that is longer than a few minutes. A 15 minute comp could easily take a couple of days to render and one effect or memory problem can cause it to fail.
Every shot in a Pixar movie is a separate project; they are rendered and edited into the final movie on a video editing system like Premiere Pro. Follow that professionals workflow.
You can easily split up your work by moving to the first shot change in your timeline, selecting all layers to that point, and pre-composing. Do it again and again until you have one-shot comps. Start rendering the comps as you go so that you can edit them in Premiere later and efficiently polish the sound tracks, timing, color grading, and everything else that goes into a finished movie.