I'm trying QuickDo by the same developer, which is cooler than dock in many ways, and FaceTime also launches with it. Makes me nervous. I don't think the developer is great with English though (he is Chinese) and is not understanding my question about it.
Edit: ok, not his fault! Some other people who have jailbroken have the same issue. It's just that most programs don't always show your processes like this does. You can restrict it and keep it from launching and eating ram, though I don't notice sluggishness.
Again, if you like Dock, try this app it's amazing and more polished.