There is an application/program called sims 4 tray importer, with it you can create a zip file of any lot or household from your library. I have an external HD where I back up my game, in it I also save lots and sims, I have file folders for the lots I use when I start a new game, like for Newcrest. Also files for sims I created and another folder for downloaded sims.
I started backing up my tray files because having no or very few things in my library made my game run a lot better. It's a bit inconvenient to load the files back when I start a game, yes. But ultimately faster loading screens and a non-laggy game is worth it.
