DDD: do I really need to load all objects in an aggregate? (Performance concerns)

Question

In DDD, a repository loads an entire aggregate - we either load all of it or none of it. This also means that should avoid lazy loading.

My concern is performance-wise.

Answer 1

In this sort of cases, could it mean that I need to redesign and re-think my aggregates?

Almost certainly.

The driver for aggregate design isn't structure, but behavior. We don't care that "a user has thousands of orders". What we care about are what pieces of state need to be checked when you try to process a change - what data do you need to load to know if a change is valid.

Typically, you'll come to realize that changing an order doesn't (or shouldn't) depend on the state of other orders in the system, which is a good indication that two different orders should not be part of the same aggregate.