I'm sorry I don't have advise for you on this project, but one "trick" I like to do is save multiple copies of big projects because after loading on too many layers, you can get odd glitches or problems.
You can also make Sequences to lighten the load of your computer.
What I do is:
Say your Project Name is -- "Food Documentary"
Once you get a good amount of layers on your project -- Save a Copy As -- "Food Documentary Draft"
Then continue to work on the project "Food Documentary" and as you go along, keep overwriting the "Food Documentary Draft" with your work, as a backup.
If you run into a problem -- you can just load up your Draft copy (make another backup copy now) and get back to work.