To be perfectly honest the hardware UART for RS232 works much more effectively for handling data. Because of how the UART is implemented, we can buffer the data much more easily. With this being said, we are still limited to a 96 byte buffer and when graphics are being drawn, it doesn't take long for it to fill and have an buffer overrun occur. The best way to avoid this is to implement flow control. Flow control is only available in RS232 mode.
We look forward to working with you in the very near future! If you have any further questions or concerns, feel free to contact us!