We're caching a lot of pages on our site, as they very rarely change and are incredibly DB-intensive to create. However, when I load these pages I very frequently get freshly created copies (the max-age HTTP header shows 3600, which is the set length for the page validity). I'm at a loss to explain why.

One possibility is that the cache is simply filling up and emptying out pages repeatedly. But I have no way of proving this idea- does anyone know if there's a tool to examine what's sat in the current cache? Or tell when an object is dropped from it? I'm talking about the whole page caching here, not adding data to the Context.Cache object.