Among other things, this document describes systems, devices, and methods for improving the delivery of resources embedded on a web page. In one embodiment, a content delivery network analyzes markup language documents that clients have requested to embedded resources, such as linked references to images, scripts, fonts, cascading style sheets, or other types of content. This analysis may be conducted on the content server and/or asynchronously, in a dedicated analytical environment, to produce delivery instructions. Where embedded resources have hostnames for which the content delivery network is authoritative, and where certain conditions are met, servers can be instructed to push additional certificates for such hostnames over the primary connection. When embedded resources have hostnames for which the platform is not authoritative, and where certain conditions are met, servers can be instructed to pre-fetch and push such resources with a signature from the authoritative origin.