This one may be a result of a misspent youth, but are there any documented instances of tracks recorded on a linux system(or on computers in general) slowing down over time? It may sound weird, but I think has happened on a least a couple of tracks I’ve worked on. It’s so subtle that I can’t be sure, it’s just a gut feeling at this point.
Only if you are referring to playing them within Ardour and you are near your DSP max (Typically near 80% but it depends on your setup), in which case XRuns along with ‘static’ sounds can make it sound like things are slowing down.
Otherwise it is either psychological or your players slowed down their playing when you were recording:)