Utterly fascinating article.
The main takeaways seem to be that 1) extensions in general wind up massively increasing CPU time (by 5-20x) when loading "example.com", and 2) ad blockers wind up massively reducing CPU time (by 4-20x) when loading a "WCPO news article".
Which makes me happy that I use uBlock (edit: Origin, thanks below), and sad that I have to use LastPass.
HOWEVER -- I feel like both these metrics are potentially highly misleading, because CPU time isn't something the user directly observes -- it might be the limiting factor, or it might not affect the user experience at all (because the CPU usage is happening while waiting for further network resources that are even slower, or the CPU usage is happening after the page has visually finished loading all relevant content).
I'd be much more interested to see how extensions like Evernote or LastPass increase the time it takes for a real webpage (e.g. "nytimes.com") to finish painting the viewport not including ads, and similarly whether adblocking actually decreases the same -- or if all the advertising stuff really only happens afterwards. (Because sites are architected differently, you'd need to compute an aggregate score across a range of common sites.)