Consider a generic super-class for all objects that should only be updated after a minimum delta
Current code has quite several objects (or even just variables at the moment) that are not supposed to be updated except if a specific amount of time since their last update has elapsed. Instead of having to carry along specific timestamp variables for each status variable we could try to have this covered by a base class from which all these status variables (converted objects) are derived.
NOTE: this might interfere with the XML serialization stuff as some of those classes can't be subclassed / inherited from.