Have flags/options in Subject Request API (SR API) to limit API response and not receive the entire batch of opted-out records. For example, 1) subset=mine. Only send ID's in my DL or API subset. 2) release=x. Only send ID's opted out since that release date. release=17 would return opt-outs submitted since launch date of release 17. 3) use a date range. This way a customer can parse daily, weekly or whatever cadence fits their use case.