MIDI playback breaks on high note density

[martin-minovski]

I tried importing and playing back the following MIDI file which Ardour plays no problem:

https://filebin.net/kw3jd9ljimahh2sr

After a few seconds, almost all of the notes start dropping.

[rncbc]

what MIDI instrument are you driving this? tested with several external synths as (internal) plugins, all polyphonic and with sustained voiced notes (eg. organ, strings) and I can't see/hear what you're talking about;

no note seems be dropped whatsoever as they keep playing right from start to end--most are 5min long, right?