Our company has been refactoring flows lately due to Apex timouts, and we're trying to decide which method runs more efficiently.

Previously, we would get a Get element to assign values of a parent record to variables; however, it appears we can also create variables on their own and then define the value of a parent record's fields as the Default Value.

Ex. {!$Record.Parent_Record__r.Value}

My question is, on the backend, is it performing a DML for each of those variables if I set the value using the example above? Which method is more efficient, and which is best practice?