The port.write() function sends 1 byte to the serial port. IF one were to create an overloaded method that took multiple bytes as input, the overload would end up calling the existing method in a loop to send all the bytes.
The "delay" with that function is NOT with having to call it multiple times.
It's time to dispense with the academic questions, and post all of your Processing and Arduino code. There may be things that you are doing (unknowingly) that limit the speed that the data is transferred at. We can't tell that without seeing all of the code.