The app on the other end of the serial port can't tell whether you used 13 Serial.print() statements to send the data, or if you pissed time and resources away using the String class. 7 calls to the constructor plus 12 calls to allocate and copy data and several more calls to the destructor take time. You don't need to waste that time.
PaulS,
Can you please link a tutorial or something that explain what the constructor and destructor are ?