An update of the PropertyConnector file is available: propertyConnectorV004. If you use FeatureLayer with a PTV xServer 1.20.x you should get the new version. It includes two optimizations for the FeatureLayer PTV_TruckAttributes.
The PropertyConnector is an xml file which connects attributes in the FeatureLayer with parameters in the vehicle profiles. With PTV xServer 1.20.x a versioning of the propertyConnector has been introduced. So make sure to always use the current version. PTV xServer versions before 1.20.x can always use the propertyConnector without version number.
The file has to be placed in the map root directory in parallel to the geo-folder, e.g. under ..\PTV_Europe_City_Map_Premium_2015_1H\detailedmap parallel to the “eur”-folder.