maximum speed PC to arduino

Hi, I was wondering what's the max physical limit in speed between the virtual COM port (USB) from the FTDI to the arduino, PC -> arduino (at 16MHz) I am trying to send messages at 300Kbps, the communication between arduinos at that speed with my application works fine, ...


People trying to use 1000000bps have reported that they have to modify the arduino serial driver (making it somewhat faster) to get reliable operation (and there isn't a lot TO the serial driver.) So somewhere around 1000000bps is probably the hard limit (I think that may also be the limit of the bit rate generator on the serial port.)