Long time user of Nuendo 4.3 on PC that migrated to mac and N7 last year. It has been working mostly fine apart from the generally more sluggish interface.
But I have one serious performance issue where I get audio dropouts. The disk meter doesn´t show any peaks and the number of tracks doesn’t seem to matter much either. My observation is that it´s a track or two that doesn’t play the first second or so after a edit and that results in a dropout or click (The other tracks seem to play fine). I’ve tried different settings and so far it seems like asio guard makes it worse. But is is very inconsistent and sometimes I can listen to a whole song without any problems and sometimes there are problems every 30 seconds. The only consistent factor seems to be that it happens at the start of edits, but it’s hard to diagnose.
My RME UFX+ (over USB3) shows no errors , neither does Nuendo (or Cubase 8.5/9).
Since I do mostly mixing the acute problem is doing mix-downs analog out to my console (Offline bounces are just fine).