@audryhome The PanelDue port is really just another serial port. It's parameters are set by M575, see https://docs.duet3d.com/en/User_manual/Reference/Gcodes#m575-set-serial-comms-parameters.
To return to your original question:
I read through the firmware doc the status messages are constantly sent through this interface. Of course these sequences take some bandwidth and this is obviously not desirable.
Can you post a link to where you read that? Usually there's not much communication on the serial or USB interface, especially if the job is running from the SD card. If commands are sent via serial, there's usually just an 'ok' for each received command. I think for a jog panel either USB or serial would be fine. You can connect both the jog panel and PanelDue at the same time, to the same serial port, or just the jog panel.
Note that newer versions of RepRapFirmware and PanelDue firmware use CRC16 for PanelDue communication; the Duet CNC pendant firmware has a branch that includes this.
For limitations of sending Gcode over serial and USB, see:
https://docs.duet3d.com/en/User_manual/Reference/Gcodes#replies-from-the-reprap-machine-to-the-host-computer
https://docs.duet3d.com/User_manual/RepRapFirmware/RepRapFirmware_overview#printing-over-usb-connection-octoprint-cura-simplify3d-etc
Ian