Does this make sense? (High CPU w/Reason)

I've been having lots of problems with this one project I finished last week. No audio, 25 channels of MIDI and DXi/VST. A couple of effects busses, some per-channel EQ and effects, a few automation envelopes. 44.1 kHz and 24-bit, running at 11 ms latency. Lately, every time I've opened it I've been unable to play it.

The project is rewired to a Reason rack that contained (in this order of build) 2 Redrums and 2 NN-XT samplers. I ended up using Velocity for drums so the Redrums weren't being used, but I had every channel on the them run into a separate input on the hardware interface. They were not connected to Sonar in any way at all. Each of the NN-XT's was running through the main stereo outs into the 2 inputs on the hardware interface and then patched into Sonar.

When I opened up the project lately, I would get a dropout immediately. The CPU meter hovers in the 50% range until the Reason project loads and then it's off the charts.

I've really been working to try and figure out what the issue could be and have tried everything I could think of. Well, tonight I decided to just pull out the 2 Redrum units and lo and behold the CPU utilization dropped IMMEDIATELY to an acceptable level (just over 50%).

It doesn't make any sense to me. I spent lots of time setting up some standard Reason templates with tons of instruments pre-wired into the hardware interface using indi outs so I'd have maximum control in Sonar. Are each of those indi outs in the hardware interface reserving, or somehow "speaking for" an amount of memory or CPU??? So that even though they're not being utilized or even patched into Sonar they're wasting space?

Sure seems that way but I've never seen or read anything that would suggest this. And I know for a fact that Reason itself would never consume anything NEAR 30 or 40% CPU for such a small project.

Has anyone else experienced this or can anyone explain it? I've looked around in Propellerheads' forums and googled around and I can find others who report similar issues, but no explanation.

Thanks,
Mike

My specs:

ASUS P4PE
Intel 845PE P4 2.4 gHz
1 GB RAM
2 80 GB WD drives
RME Multiface, 2.62 drivers
Matrox Millenium G550 Dualhead
Sonar 3 PE
Reason 2.5