It looks like you may experiencing another thing that i've complained
about... pd's alsa midi connects to all MIDI inputs and outputs that
it can.. this includes alsa's MIDI through.. so everything that you
send out gets echoed back into the input.. SUPER annoying.

run aconnect [or easier, though not great, aconnectgui] and see if
that is the case for you.. disconnect pd from the alsa through port.

> This makes me think I'm trying to send too much data in too short
> intervals...? Is there a handy way to limit the density of my output? (i
> think its not not [drip] as it has to stay realtime)