Any role for the Server-Timing field?

[LPardue]

Since we're using HTTP, you might want to think about whether there is anything that the Server-Timing field could help measure; see https://w3c.github.io/server-timing/#the-server-timing-header-field. The field is extensible, so the action here is to consider if there are optional metrics that responsiveness servers might be able to expose for some purpose, and document that here.