I have figured out that, in my case, the logitech cam latency starts when OBS reports more than 40% CPU load. This doesn't impact my other sources however, even running simultaneously. Not connecting to FB or YT, as I thought; those connections are just making the CPU work harder, and the logitech cam starts lagging immediately, as the CPU load rises. Same thing happens when I add certain process-intensive backgrounds, ie CPU load goes up even if not actually connected to online host, and latency begins. I can stream without latency if I hide those backgrounds. Strangely, this doesn't affect other cameras, just the logitech. I've turned off autofocus, auto white balance etc etc. Something fishy about the logitech. I wouldn't recommend it. But now that I've bought one I'm damn well gonna make it work ;)
