FasterCanConvertMethod

 static HashSet<Type> _classesConvertable = new HashSet<Type>();
 static HashSet<Type> _classesNonConvertable = new HashSet<Type>();

 public override bool CanConvert(Type objectType)
 {
     if (_classesConvertable.Contains(objectType)) return true;
     if(_classesNonConvertable.Contains(objectType)) return false;

     if (typeof(IContainSecretData).IsAssignableFrom(objectType))
     {
         _classesConvertable.Add(objectType);
         return true;
     }
     else
     {
         _classesNonConvertable.Add(objectType);
         return false;
     }
 }