Should CNBC be “freaking out” over a tumble in Nielsen ratings? Nah. It is, after all, still the No. 1 financial-news television network. But CNBC shouldn’t get too complacent, either. CNBC CMCSA +0.84% , according to a person familiar with the situation, recorded its sixth consecutive year of record financial performance in 2011, amassing about $400 million in operating profit. It is clearly one of the most lucrative and valuable members of the NBC Universal family of channels. But there may be unrest in paradise, just the same. The New York Daily News, using anonymous sources, says CNBC executives are “freaking ... (full story)