I understand that the data sourced to the API are cached, but I'm seeing some fairly extreme discrepancies between reputation reported by the API and apparent activity on the site.
Jon Skeet's last answer has five upvotes and was accepted, so the total rep should be 65. The question was asked three hours ago at the time of this posting, and Jon's answer came immediately after. Jon's rep reported for that answer at this time, by the API, is still only 15.
How often is the cache used by the API updated?