ops per seconds improved and Gyro/Accelerometer calculation changed. ESC delay measured. Seems to be around 70msec.

Delay between PWM input (red) and rotation time measurement (green), less than 100msec minus 30msec for 1 rotation = less than 70msec.
The final copter main loop runs at around 130Hz – what turned out to be fast enough. However there seems to be some optimization potential, e.g. by using a multi-threaded microkernel stack to avoid blocking response times in the different protocol requests to the sensors or to use optimized floating point calculations, e.g. by fixed-fraction integer arithmetic.