Earlier quoted context omitted.
Interactivity with viewers. The best streaming experience for both streamer and viewers is when they can interact, and any latency over 500ms or so makes that a true challenge if you're trying to have a conversation where context is important. Being an introvert that doesn't like it when people pay attention to them at all for any reason, I haven't really experienced this, but that's what everyone says.
There is no realtime interaction on stream anyway if you have more than a handful active chatter. And lag is high by default if the streamer is doing more than just chatting, like playing a game, building some stoff or reacting to a video. So which experince are you talking about?
CPU usage on the streaming PC does not increase latency unless the PC is severely under spec. CPU usage increases CPU usage. That's it. Encoding usually happens on a GPU, and scene composition happens on the CPU, which is either a zero-copy routine or a very fast memcpy.
My point is that from what you're saying, it seems clear to me that you are not aware of just how good WebRTC is at this kind of thing.