Duration

- Removed legacy duration value mapping, which causes much performance
  degradation.

src/TDB2.cpp

@@ -580,7 +580,6 @@ void TDB2::modify (Task& task, bool add_to_backlog /* = true */)
 {
   // Ensure the task is consistent, and provide defaults if necessary.
   task.validate (false);
-  task.upgradeLegacyValues ();
   std::string uuid = task.get ("uuid");
 
   // Get the unmodified task as reference, so the hook can compare.