What is the most stable OS for Pro Tools 10?

[Joe Porto]

It may depend on your machine. I have a 2008 Harpertown Pro 8-core. 10.6.8 gives me more tracks at a lower sample buffer than 10.7 or 10.8. This is both with Logic and with Protools HD native. I initially was running PT10HD native on 10.7.2, and wasn't getting the performance I expected. I reverted to 10.6.8 and haven't looked back.

In fact, I have a 10.8.2 partition that I am currently testing with the new UAD 64-bit software, and I can't get it stable under 128 sample buffer, where on 10.6.8, I can run Logic at 32 sample buffer playing back 60 tracks.

Maybe 10.7 and 10.8 are optimized for the newer i5/i7 machines?

[Doc Mixwell]

Mac Pro 8-core here
2.33 Dual Quad core 2009
10.6.8 Snow
PT 10.3.3 Native

USB and PCIe interfacing

solid
as
a
rock

[Sean Sullivan]

Doc, we have similar set ups (8 core 2.26 Nehalem)

What H/W buffer, host processors, cache size, and CPU useage has given you the best results?

[Doc Mixwell]

Buffer changes with workload
I track flawlessly at 64 samples
mix might go up to 1024 (depends on the mix)
7 processors
99%
using 12GB of 16 for disk cache
which is like nothing - and I've got room to grow the sessions huge

I love life

[Sean Sullivan]

So you are using 7 of 16 "virtual processors"

I haven't found the right "combination" yet, but I'll give your set up a go.

[Joe Porto]

Adam, like me, is running PTHD, which has disk caching. This allows PT to load the entire project into RAM, and boosts performance significantly. You mention PT10, but not HD. If you do have HD, you should take advantage of Disk Caching.