Fastest communication between Arduino and PC I am using an Arduino 2 which collects data from a set of microphones and stores it in an array of unsigned short of 40000 elements and sends them to the PC via Serial USB. 

It is working but I'd like to obtain more speed without any errors.

Can you suggest me the best way to do it? Even changing communication.

Thank you
Switch to using SerialUSB instead and use the other USB port. The baud rate is meaningless then - it runs at the speed of the USB port, which is a lot faster than serial (Linux reports it as 480Mbps, though I can't see an 84MHz chip doing that...).

void setup() {
    SerialUSB.begin(115200); // The number is irrelevant but it needs something in there
}

void loop() {
    SerialUSB.println(millis());
    delay(100);
}


For greater throughput you could devise some packet-based binary protocol to optimize your data flow to use less bytes.