Recently, I've been obsessing about decoupling timing in DDD.

No matter how much I think about it, I feel like I won't find the answer till I actually go through it. So I'm looking for other perspectives.

If you are someone who maintains application designed with DDD, and traffic of one domain starts getting higher, when do you decide it's time to separate by control plane / data plane?

Do you treat this as an architectural concern from the beginning, or does it usually emerge later as the system grows?

I'm curious how people here make that call in real.