Thank you for your response, this is the answer that I had previously expected, because I had previously contacted RajaOngkir and said the same thing, they assumed that the problem “the performance that occurred was not from their server but from the plugin” so they were not responsible for it
and I have also told them that for now I am using the Pro user API which should get a faster server than free users,
but the method regarding reducing the number of active couriers is a good idea maybe I need to try it
