N6 MMC via MIDI woefully slow

I am using a “Mackie Controller” (MC), with 3 MIDI In-Out hardware connections via two MidiSport 4X4’s from the DXB200 to my Mac-Pro. This has worked well in N4, not so well in N5 and now N6 is really quite bad.

The main issue is what appears to be a long lag in Nuendo sending back time code, transport and meter status. Nuendo responds fine to any MIDI device transport or fader commands from the MC. But the clock and the transport LED’s (status) on the MC have to play catch up with N6. So upon hitting play the clocks wind in time with the MC getting farther and farther behind as time goes on. Hitting stop the MC’s time display is still running and playing catch up. The longer you play a song and then hit stop, the longer the clock takes to match up, and then light the STOP LED. FFWD and REV exhibit the same behavior, even perhaps exaggerated. Incidentally I see the same behavior on my Frontier Tranzport, but not on the “Cubase iC” control via iPhone. It almost appears to be USB/MIDI related.

Using Snoize’s MIDI Monitor, you can see the control data continue to broadcast from N6 to the MC long after a command is sent. And I have also been noticing a continuous stream of MIDI controller data when N6 is stopped, on at least one MIDI hardware connection; its visible from Snoize as well as the N6 MIDI meter showing constant MIDI output data.

I can stop the symptoms if N6’s “main” mixer is NOT displaying any audio channels, or by disabling all but about 2 audio tracks. But of course this is pretty useless because now my MC shows no feedback to Nuendo for the tracks, thus no external fader functionality.

It’s making me crazy.

Digging in further, I see the lagging data on my MIDI monitor even using my space bar for START/STOP.
Start a project with one track, everything works fine. Duplicate the tracks 3+ times and the lagging starts.

I’m responding to my own post in hopes that somebody will have some insight, the silence is deafening.

I have now observed that the lagging data is also a function of how many hardware connections are being sent from N6 to the Mackie Controller. Using 8 channels (one MIDI hardware connection) all seems fairly sane, but as soon as I add another 8 (i.e. a second MIDI hardware connection) the symptoms of my original post appear.

Here’s hoping someone might have an idea.