Hello I am trying to make an android pic sharing app like insta, but it doesnt work efficiently every time a user request hashtag like #pic it goes to server run query nd get result, it make process repetitive and slow. is there any other way to get this done

If i go with push notifications or websockets but still the problem persists, if i need to implement this like a user follow 100 people and i want to display recent posts to him how it will be done if i query simply using mongoose and paginate it for infinite scroll in my app it will take too much time and for every page it will search from all post from database.