What are your computer's specs (CPU speed, RAM)?
If you have an older computer, there's a good chance that this behavior is being caused by the extra processing from the motion detection logic. We can figure out if that is the case by dialing back the motion detection processing a little bit.
To do so, simply copy and paste the following line of text to an Applications > Utilities > Terminal window and hit Return:
defaults write com.skjm.icamsource MotionDetectionWait -int 2000
The number at the end is the number of milliseconds that the iCamSource will wait before checking for motion. You have to restart the iCamSource for any change you make to have an affect.
