FYI ... when I stumble-upon certain mainline sections, such as Meditations or Perl Monks Discussion, ... and for some (but not all?) threads listed on those pages ... I lately observe that the content is often many days(!) out-of-date ... until I log in.
I think that this problem varies from one major-topic to another ... e.g. Seekers vs. Meditations vs. PMD.) Specifically, I think that I am seeing “cache artifacts” that seem to vary(!) between “headline” pages and “particular threads” within a topic ... but, not necessarily consistently. Sometimes I think that I am seeing a “fresh” page, while sometimes I think that a “neighboring” page is, in fact, “very stale.” (I generally suspect that “the headline page” is the one, of the two, that is “very stale.”) Given that I dump my local browser cache many times a day, I do not believe that local-caching is the root cause of this problem.