[LAU] Sanity check needed: Fons's Auto Wah on 64-bit system and CPU usage?

I've been running Fons's great Auto-Wah on my 32-bit Netbook for many months now, using it live constantly, and I love it. I'm going into the studio Friday, so I've dusted off my 64-bit Core 2 Duo system and putting it through its paces. Turns out that on my Core2Duo, JACK RACK running Fons's auto-wah plugin sucks up 6% CPU even if there is no sound going through it. I asked Fons about it; he can't duplicate the problem since he doesn't have a 64-bit system. Hell, I can't even duplicate it on my 32-bit system; it's 64-bit dependent. I looked at the output with Bitmeter at Fons' suggestion, and it seems there are no denormals, inf's, or nans-- just a very small -230dB DC offset in the code (probably to avoid denormals). The CPU usage ramps up before any signal is fed into the plugin. It runs normally when there is signal, but then it keeps sucking up CPU afterwards. I'm feeding it from fluidsynth, and bitmeter says that it isn't sending anthing at all during silent moments. It doesn't run away to 99% CPU (or 50% on a Core2Duo), like it would if there were a denormal. But still, why is it using up CPU when there's no signal? That seems odd. And why only on my 64-bit machine? FWIW, the 64-bit and 32-bit machines I have are even running the same kernel and RT-patch versions (2.6.26.8-rt12). Can someone with a 64-bit system help me by trying to duplicate the problem? I'm looking to see if JACK-RACK running just Fons' plugin uses as much CPU with silence as when there's signal running through it. Oh, and in case it's setting-dependent, here is the rack with the settings I'm using: http://restivo.org/misc/clavy-phaser.rack -ken