Well, I have answered this question before, but that was under the assumption of the Data Structures Already established. But, If I get to make one up, that I can abuse.
I would go with a Cache-Hash Data Structure. A Hash is sort of like valet parking. Each car is given a ticket and stays in one spot. As long as you have the ticket, you can access the car anytime you want. So in a hash, you use a Key to sort and store anything you want. It also adds a layer of cybersecurity too.
But I want to make it into a cache as well. Cache is like mini-memory a computer uses for whatever you use the most. Like visiting the same website everyday? That would be stored in cache for faster access to said website. It is also a specific type of Hash Structure too, so double Hash.
So basically, I want a Fetch Modus with 2 bars, one smaller for more frequently used items, and one larger for other items, all in a Hash Structure.