When communicating with the Robovero over a serial connection (through the mini USB port), how fast can the commands be processed?

From a C program, I've opened a serial connection and initialized the robovero with the following commands:

1. \n (new line for robovero to detect line termination)

2. promptOff

3. resetConfig

4. roboveroConfig

5. configure and control PWM

If I send these commands to fast, some of them aren't processed by the robovero.  Waiting for the serial device to finish sending the data ( tcdrain() ) prior to sending the next command helps a little bit, but I've noticed there are still occasions where the command is 'dropped'.

What's the right frequency to send commands to the robovero, such that no commands are dropped?