Abstract: We disclose techniques for varying the caching of content provided by a content server as a function of the server's load. When the server is lightly loaded, freshness of the content is maintained. As server load increases, caching time increases, to trade off freshness against transmission time. Similarly, when the server is heavily loaded, users might quickly be served cached content that is only slightly stale—as opposed to content that was fresh at the time of the request, but which becomes materially stale by the time the server completes serving the response. The server's load can be measured by its response time to a request, or otherwise. Optionally, the system can override the load-based caching by defining classes of requests that automatically trigger updating or refreshing (e.g., cache expiration) of related information in the cache.