Update customer phone numbers

Hi experts,

We need to update customer and contact's phone numbers on a daily basis to SAP. We receive this information from a third party, and we talking about ~5000 customers and 3 - 4 contacts per customer we need to update. We are using functions BAPI_ADDRESSCONTPART_CHANGE and BAPI_ADDRESSORG_CHANGE from an external program, but it is taking too long to finish.

Is there any way to make this process faster? Do you think that creating an RFC that takes all customer + contact phones into a table and process it can make the difference in performance?

Thank you.