ofVideoGrabber freezes audio (and globally slows down the computer)

I’m using ofVideoGrabber to capture two streams of video, one from my onboard laptop webcam and a second one from an external usb webcam. The problem is that when I launch the app using this external webcam, the audio in my computer freezes completely (I’m running audio not from OF, through an external sound card).
I have tried using two different external webcams, both produce similar results, except that one completely blocks everythin while the other has a more erratic behavior, highly distorting the audio signal anyways.

I asume this is a problem with the way OF handles video, because when I access the camera with other applications (skype for instance) I have no problem at all, and the audio signal flows perfectly.

Any ideas?


I have performed some further tests, apparently this does not happen when I use the onboard soundcard (only with an external USB soundcard), nor does it happen when I use only one webcam at a time. Also, CPU is always under 20%.