This problem is common to Nuendo 6 and Cubase 7 on OS X.
I tested long recordings (between 30 and 60 minutes) of eight channel FLAC files at 192 kHz / 24 bit.
When the recording is stopped, Nuendo will freeze for a period equivalent to about half the recording time (around 30 minutes for a 60 min recording). During a typical 30 minutes freeze, the computer hard drive will be read from at maximum speed for the first 25 min (about 200 MB/s on my MacBook Pro with a standard HD and about 340 MB/s on a MBP with a flash drive) and, for the last 5 minutes, the computer will read and write to the HD, hovering between 15 and 20 MB/s. All the while displaying the spinning beach ball.
Steps to reproduce:
- 1- Create a project with FLAC as file format, 24 bit and, since it’s related to the file size, the highest sample rate your audio interface will allow.
2- Add a multichannel (maximum eight, the FLAC limit) audio track, record-enable it, start recording (I record white noise from unconnected mic inputs).
3- Record at least 30 minutes non-stop.
4- Stop the recording.
Nuendo should then display the spinning beach ball for quite a while…
This was tested with Nuendo 6.0.2/0.3 and Cubase 7.0.2/0.3 on a MacBook Pro with a 500 HD and 16 GB of RAM, a Retina MacBook Pro with a 256 GB flash drive and 8 GB of RAM and a Mac mini with a 1 TB HD and 16 GB of RAM. I tested with a Metric Halo ULN-8 interface and a RME Fireface 800 interface. All with OS 10.8.3.