Question:
Answer:
In versions up to 4.1, whenever you change the Memory Settings (with the exception of "Processing threads") the server actually goes through an entire restart which therefore of course refreshes the cache.
With the introduction of 5.0, quite a number of things can trigger a cache reset. For example, if you "Check for Updates", upon completion of downloading the updates, the cache is reset. Resets also occur when you toggle any of the plugins on/off, and in some cases, when you create a blog.