around there & upwards. You've listed one of the big problems with rabbit @ volume - inevitably/unavoidably you are going to have consumers go down or so slow. At a high enough volume you're heading for a crash/partition quickly if you cant respond fast enough (where "fast enough" is a time window inverse to how high volume the queue is). Its a crappy failure mode to have a sword hanging over you like that.

other log-based messaging technologies like kinesis, kafka, etc do not care if a consumer goes down & are thus much safer.