ObjectiveCore / Style / Events / Frame - polishing the execution path for better performance - make use of the Blizzard_ObjectiveTracker bitfield values to ensure compatibility in possible secure hooks - avoid full updates when possible (using said bitfield values to indicate targeted sections) - extreme streamlining of event handling layout: specific reason updates are invoked from API hooks; broader updates are invoked by when the event listener catches something vague like 'QUEST_LOG_UPDATE'