OP here. This article generated some attention and traffic. The claims contained in it are incorrect. After another contact with CF support, it turned out that the Bot Fight Mode behaves differently for Free and PRO plans. That's what caused the instant improvement after upgrading. Another way to resolve the issues I was experiencing would have been to disable the bot fight mode altogether or add a custom page rule disabling it. My website never experienced any traffic throttling. I've decided to remove the article, to stop spreading the misinformation about CF services.