> It takes a non-0 amount of time to load large indices into memory (upwards of 5 seconds, depending on your choice of disks and arrays), and to iterate through

> It takes a non-0 amount of time to load large indices into memory (upwards of 5 seconds, depending on your choice of disks and arrays), and to iterate through large indices once they are in memory. This is why MongoDB recommends all indices fit in memory