Could muting the system volume cause coreadiuod to use lots of CPU?

I mute and later unmute the OS X system volume with the following code:

void SetMute(AudioDeviceID device, BOOL mute)
{
    UInt32 muteVal = (UInt32)mute;

    AudioObjectPropertyAddress address = {
        kAudioDevicePropertyMute,
        kAudioDevicePropertyScopeOutput,
        0
    };

    OSStatus err;
    err = AudioObjectSetPropertyData(device,
                                     &address,
                                     0,
                                     NULL,
                                     sizeof(UInt32),
                                     &muteVal);
    if (err)
    {
        NSString * message;
        /* big switch statement on err to set message */
        NSLog(@"error while %@muting: %@", (mute ? @"" : @"un"), message);
    }
}

The value of device is determined with

AudioDeviceID GetDefaultAudioDevice()
{
    OSStatus err;
    AudioDeviceID device = 0;
    UInt32 size = sizeof(AudioDeviceID);
    AudioObjectPropertyAddress address = {
        kAudioHar开发者_如何学CdwarePropertyDefaultOutputDevice,
        kAudioObjectPropertyScopeGlobal,
        kAudioObjectPropertyElementMaster
    };

    err = AudioObjectGetPropertyData(kAudioObjectSystemObject,
                                     &address,
                                     0,
                                     NULL,
                                     &size,
                                     &device);
    if (err)
    {
        NSLog(@"could not get default audio output device");
    }

    return device;
}

And I also check whether the system volume is currently muted, with:

BOOL GetMute(AudioDeviceID device)
{
    UInt32 size = sizeof(UInt32);
    UInt32 muteVal;

    AudioObjectPropertyAddress address = {
        kAudioDevicePropertyMute,
        kAudioDevicePropertyScopeOutput,
        0
    };

    OSStatus err;
    err = AudioObjectGetPropertyData(device,
                                     &address,
                                     0,
                                     NULL,
                                     &size,
                                     &muteVal);
    if (err)
    {
        NSString * message;
        /* big switch to set message */
        NSLog(@"error while getting mute status: %@", message);
    }

    return (BOOL)muteVal;
}

All of this seems to work fine -- the system mutes and unmutes with the same behavior as if the user hit the mute key on the keyboard (unmuting restores the last volume set before muting, etc).

I have noticed that at some unspecified time after my program does this, coreaudiod begins to consume a lot more CPU than normal (in my case, this is only around 5-7%, but ordinarily it reports 0.0% in Activity Monitor). As far as I can tell, I'm using the Core Audio APIs correctly there, and nothing looks like it should be causing any glitches in coreaudiod, so I'm hoping that someone can either point out an issue with my code, or point me towards what else (possibly unrelated?) might be causing the CPU usage in coreaudiod. I should also note that when I observe coreaudiod using more CPU than normal, there's no sound playing, and the system is unmuted.