I'm probably doing something really dumb, but I justed started a new Juce app, added an AudioDeviceManager and a AudioDeviceSelectorComponent to a single Component app. The Audio engine callback thread only seems to run when the mouse is moving. The little blue input level lights only change when the mouse is moving, and even then, they decay very slowly.
It doesn't use much CPU, only 2% or so.
Visual Studio 2010 on Windows 7.
My setup is as simple as:
devManager.initialiseWithDefaultDevices(2, 2);
devManager.addAudioCallback(this);
addAndMakeVisible(devSelector = new AudioDeviceSelectorComponent(devManager, 2, 2, 0, 0, false, true, true, false));