How well will my app scale given these performance with one user and 1m total documents?

I am building an APP with MERN. I have created 1 million fake users with random data on MongoDB Atlas.

There are 2 foreseeable intensive query reads that my app must be able to handle.

Currently, I have built one of those two queries. And I am the only active user, of course. I have built a few indexes.


  • On good runs, this query returns in about 1 second
  • On bad runs, it is taking in about 3 seconds

This is of course with just one active user, though 1 million documents in the collection. In realistic scenario, can this APP scale to 1 million registered user and a realistic number of simultaneous active users?

Why or why not?