what kind of performance should I be expecting?

I’m mocking up a full John Williams score right now, and I’m running in to some performance trouble. My machine specs are:

Mac Pro 5,1
2 x 2.66 GHz 6-core Intel Xeon
64 GB ram
1 system HDD, 5 SDD sample drives
Cubase 7.0.4
Buffer at 2048
LASS 2, Cinebrass, Cinewinds, Spitfire Perc, some waves plugins

During MIDI playback in particularly dense areas of the score I get instrument drop outs, and the 2048 buffer barely keeps the pops and clicks out. I would think a machine like this would be able to run a full midi score without much trouble, or nearly as much trouble as I’m having at 2048. Is there something I’m missing that could improve my performance in Cubase, or is my system not as powerful as I though it was?

I should add that I changed Kontakt’s preload buffer size to 240 kB, which seems to improve my performance over a 60 kB preload.

Have you installed the “Mac Performance Switch” that Steinberg released last week? I’m not sure it will help your situation since it was written to prevent that 2 to 3 second performance spikes mac users were seeing.

https://www.steinberg.net/forum/viewtopic.php?f=175&t=39738

I did try that, even though I wasn’t experiencing any 3-4 second random spikes, just dropouts and pops/ clicks during playback. However, after placing the text file and reopening the project, I started getting 3-4 second spikes. So it seems to have caused exactly what it was trying to remedy, at least in my computer. Removed the txt file and it’s back to normal.

So I’ve gone and taken out all plugins, and all the instruments that weren’t being used in the score. My VST performance meter barely goes past 35% now, but I still get instruments dropping out.

What audio interface are you using? What happens at 1024 buffer?

I’m using a Profire 610 with the latest drivers. At 1024 I get heavy drop outs, so bad that it starts skipping like a cd when more than 9 instruments are playing at once.

Does my interface need to be upgraded, and if so could you suggest a good fit for my needs?