Slow mode

Set a delay of a few seconds and each viewer can only post once inside that window, so a chat moving too fast to read slows to something a host can follow. Moderators switch it on as a room fills and lift it when the stream quietens. It is a pacing control rather than a moderation one. Spam coming from many accounts still gets through, only at a slower rate, which is what members-only chat and account age requirements are for.