I'll have a look at the patch tonight. I have to work soon.

So far, the MIDI sync works as it should. I've added a [+ x] to the MIDI clock counter to fine tune the timing, so the beats of the Rhythmboy and Traktor are in sync.

The last bug I have to fix are some performance problems: When I switch pages (tracks 1-4 or 5-8) the redrawing of the LEDs causes the Rhythmboy to stutter for a moment. You can see how the beats are delayed, for example when you look at the result of the timer that measures the time between two beats. Usually it is around 125 ms for 120 BPM, but when I switch pages, the value drifts a lot for on second.
I've already tried to add small delays to the redrawing of the different tracks, but this didn't help. The redrawing only occurs of the MIDI output to the QuNeo (the LED output) is activated, else it doesn't stutter.
Do you have any idea how to reduce this stutter?