Does individual users send activities directly? I thought only users of your instance and remote federated instances send traffic to your instance, so this change would only affect data coming through from the larger instances?
Also, what’s happening with the original request while they remain in queue? Say for example if large-instance.com is sending 11 updates to your instance; while your back end server is processing the first 10, what’s happening with the 11th? Does it get put on hold while your back end churn, or does it get a 200 OK response, despite the request may be failed at a later date? Neither of which seems ideal — if the instance get put in a queue waiting for a response while you churn, or worst yet, if your backend fails and your buffer is waiting X seconds to time out each request, you’re going to hurt the global federation by holding up a spot in their out going federation queue; if the instance is sent with a 200 OK and your backend eventually fails, you’d lose data as the other instance wouldn’t know they’d need to retry.