You're not following me. It's a single serial bus at 3,125 bytes per second. Expressive controls like polyphonic pressure take at least two bytes, sometimes three: that's for a single message. A note on is typically three bytes, channel, key and velocity.
All these messages have to take turns. It's not a tracker, or a modular synth, where you can parallel click rise times electronically: it's not DINsync, where a chain of voltage pulses synchronize individual sequencers and aren't themselves notes.
1000 messages a second (at three bytes for each note-on) seems like a lot but it really isn't. With your 16 instruments (any drum, the xylophones, whatever) you can fire about 62 notes on all instruments per second. That seems like a lot too, but it's a hard limit, and it means your sixteen instruments have to 'blur' across 16 milliseconds to all fire off a note.
That means every time you fire all the instruments as one click, instead the attacks make up a 960hz tone. That's NOT one attack. Humans on percussion instruments can do better than that. It's the equivalent of 5.5 feet of space between speakers playing back: if you're time-aligning a tweeter and a midrange to produce a unified click, and you misalign one of the drivers by putting it five and a half feet back from where it would be, you'll notice the misalignment. Midi's timing issues are also noticeable.
Each MIDI port is serial, but multiple ports on an interface can operate in parallel.
Consider that Hollywood composers and music producers are able to use MIDI without issue for live-previews of orchestral compositions and live recordings and performances. The problem you are raising simply doesn't exist in the real world, accept that there are things about MIDI you don't understand and move on.
I can certainly accept that for you, the real world is multiple MIDI ports in parallel. You're correct in that if everything's in parallel on as many ports as you need, that'll help a lot.
Still ain't quite DINsync or modular, but there ya go :)
All these messages have to take turns. It's not a tracker, or a modular synth, where you can parallel click rise times electronically: it's not DINsync, where a chain of voltage pulses synchronize individual sequencers and aren't themselves notes.
1000 messages a second (at three bytes for each note-on) seems like a lot but it really isn't. With your 16 instruments (any drum, the xylophones, whatever) you can fire about 62 notes on all instruments per second. That seems like a lot too, but it's a hard limit, and it means your sixteen instruments have to 'blur' across 16 milliseconds to all fire off a note.
That means every time you fire all the instruments as one click, instead the attacks make up a 960hz tone. That's NOT one attack. Humans on percussion instruments can do better than that. It's the equivalent of 5.5 feet of space between speakers playing back: if you're time-aligning a tweeter and a midrange to produce a unified click, and you misalign one of the drivers by putting it five and a half feet back from where it would be, you'll notice the misalignment. Midi's timing issues are also noticeable.