Either way, I only get bad performance from a few tabs at a time, usually a Fandom wikia or the pinned Gmail tabs. The first can be solved with a few seconds on about:performance, and the second well... after reading this article and Gorhill's reply, I opened a Fastmail account. We'll see how it goes. But if they're really planning to put all users at risk with an automatic update, Google has finally crossed the evil line.