Add a bit more guidance on handling work after dev service startup

Author: holly-cummins

_posts/2026-01-05-new-dev-services-api.adoc

@@ -204,6 +204,8 @@ This isn’t possible, because a dev service would never be started in the build
 To pass configuration to the application, you can
 https://quarkus.io/guides/writing-extensions#injecting-configuration-into-recorders[use recorders].
 
+In general, the Quarkus philosophy is to move work from application start to build-time, not the other way round. If you do need to move work into a `postStartHook` or recorder, try to move as little as possible, to avoid negative performance impacts. Often, code needs to know that a Dev Service *will* be created, but not the actual address. This can be handled as part of the normal build flow using a marker build item, leaving the bare minimum to execute as part of the hook.
+
 ==== How can I publish links to my service in the Dev UI?
 
 If your service has an admin console, it's a nice pattern to publish a link to it in the Dev UI.