[Twirrim]

First you get a PUSH_PROMISE request that is a single frame. It's tiny.

That tells the client what the server wants to send.

The client can respond with a an RST_STREAM frame https://http2.github.io/http2-spec/#RST_STREAM Again, that's a single frame.

By design it's meant to be extremely small and quick even on high latency, and/or low bandwidth connections.

[thecompilr]

You imply that there is a delay between the promise and the push, but it is not necessarily so. In fact the promise and the data may be sent in the same packet.