Mivas: I tried to change settings and looking for mods but without any solid result. The best I can do now is set Kill Cam to None which means that killing outside of VATS system doesn't trigger slow motion scenes. Hm, I guess I will eventually play it as 'run&gun' Fallout 3 again. Shame.
I've only been able to try out the Less Intrusive Kill Camera that Siannah suggested for a couple of minutes yesterday, and so far the kill cam still happened, but it moved from first person to third, while I was still able to see what's going on... so that's good.
I'll also try the second one and will test them both today, hopefully it will get better...
but I still don't understand why such obviously stupid concept can't be turned off :)