A record-triggered flow must update a field on the same record that caused it to run. Which run timing performs this update most efficiently, and why?
- AAfter-save, because only after-save flows are able to read the field values on the record that triggered the flow.
- BAfter-save, because a before-save flow is not permitted to assign values to fields on the triggering record at all.
- CBefore-save, because the change is applied in the same transaction before the record is committed, avoiding a second save operation. Correct
- DBefore-save, because a before-save flow can call Apex and email actions that write the field more quickly than a save.
Why A is wrong: Tempting because after-save flows are common, but wrong: both before-save and after-save flows can read the triggering record's field values, so this is not a reason to prefer after-save.
Why B is wrong: Tempting through confusion over before-save limits, but wrong: assigning to the triggering record's own fields is exactly what before-save flows are designed to do.
Why C is correct: Correct: a before-save flow modifies the triggering record in memory before it is written, so the same-record field update needs no extra DML and runs fastest.
Why D is wrong: Tempting because before-save is the right timing, but the reason is wrong: before-save flows cannot invoke actions such as Apex or email, which is why they are limited to fast field updates.