Adam Dalliance on Nostr: If I boost your message it looks like an "Announce" message is sent from my server to ...

If I boost your message it looks like an "Announce" message is sent from my server to my followers, who then ask your server for the contents.

But if my follower's server already has a cache of your message the server will just send that cache to the followers.

So it's fetched by my followers from your server rather than being addressed to my followers from your server.

So yeah, your server is gonna be dealing with load.