yan5619:
Thank you for your swift reply.
I need a real time monitoring GUI, that is why I am streaming the data over the serial port (via Bluetooth) into Processing (and then plotted into a graph).
The term 'real time' means different things to different people. What does it mean to you? What sort of update frequency and latency are you trying to achieve? How much data needs to be transferred at each update? If you are only displaying the values on a screen then you can probably afford to update them considerably slower than 100Hz. In that case you might want to separate the sensor handling code from the output code so that you can perform them at different frequencies - you probably want to do your inertial extrapolation as frequently as possible to minimise cumulative errors and you don't need to pass all that data through the bottleneck of your serial port.