CPU Usage Spike - Pro Tools M-Powered

[evenyre]

Hello,

I will attempt to make this message as short as I possibly can. Forseriously. It's a simple problem, but one that's difficult to explain.

I am having a problem with CPU usage spiking in Pro Tools M-Powered.

The Status:

I am working on a typical rock session. There is a total of 19 tracks (15 audio, 4 auxiliary, 1 master). All regions are consolidated, automation is scarce, and there are no fade files. Many RTAS plug-ins are used, and there are no virtual/digital instruments/modelers are being used.

The Problem:

In the beginning of the session, and during playback, all tracks/instruments and plug-ins are active, and my CPU usage is around 55%. As the song progresses, it reaches a point where all instruments stop (part of the song's composition). During this silent portion of the song, my CPU usage jumps to 97% and my system begins to bottleneck. At this point, there have been no new tracks or plug-ins introduced; there is literally nothing going on. This seems very counterintuitive, because all tracks and plug-ins are active through the course of the song, and my CPU usage is stable, but when there is little or no audio, my CPU usage spikes. The problem is not random, and occurs in a very precise location.

Solutions I have tried:

Increased/Decreased Hardware Buffer Size, Increased/Decreased DAE Playback Buffer, Sub-mixed the session into new session, used an external hard drive (7,200 RPM), used the maximum number of RTAS processors, disabled Bluetooth and Airport, and deleted ALL unused region files.

Again, the problem is not random, but very precise. Obviously, my computer is capable of playing back an entire mix with each plug-in active, but shows no capability of playing an area of silence with no plug-ins active.

Could it be an issue with Pro Tools 8? What can I do?

Thanks in advance, DUC!

Here are some images of the what's actually going on:

CPU Usage at 55% (all tracks and all plug-ins):http://i66.photobucket.com/albums/h2...tmelody/55.png
CPU Usage at 97% (2 tracks, four plug-ins):http://i66.photobucket.com/albums/h2...tmelody/97.png
Playback Engine Settings:http://i66.photobucket.com/albums/h2...backEngine.png
Memory Usage:http://i66.photobucket.com/albums/h2...ody/Memory.png
Narrow Mix View:http://i66.photobucket.com/albums/h2.../NarrowMix.png

[TOM@METRO]

This could be denormalization, a known issue with SansAmp. If you are running SansAmp try inserting a dither plug-in just before the SansAmp. The older Dverb also had this issue with the same workaround.

[evenyre]

Thanks so much, Tom! Turns out that there was a denormalizing issue with the Joe Meek Meekqualizer Plug-ins within the session. I slapped a 16 bit dither plug-in before each of them, and now my average CPU usage is 31%, with a peak at 42%! Thanks, again. Helped a bunch.