None of this is particularly convincing.
> That's because they have explicitly stated that they will not deprecate the observational webRequest API, which has exactly the same privacy considerations as the content blocking API.
It's still a substantial improvement if popular extensions that don't need to use observational webRequest (ie. content blockers) no longer use this more expensive method. It's a leap of logic to suggest that supporting observational webRequest means that the simpler content blocking API has no benefit.
> Furthermore here you can see a tweet from Justin Schuh, lead of security and privacy on Google Chrome, where he claims that the "sole motivation is correcting privacy and security deficiencies" (which I just debunked as being a possibility), not performance (...) So between Justin Schuh and Simeon Vincent (author of the post you linked), who is lying? It must be at least one of them.
Neither. The change may be motivated by privacy and security but as Simeon Vincent explains, it also has substantial performance benefits. I'm not sure how you logically leap to the conclusion of "this has no performance benefits" from "we did this for privacy/security reasons".
It's also extremely misleading to compare the performance of a content-blocked site to internal browser performance. You know what has the best overall performance? An extension that blocks the whole page; 0ms speed, the best performance, almost zero battery drain, except that this hypothetical extension consumes substantial resources on its own. But hey, the 0ms page speed makes up for it. It'd be pretty silly for the Chrome team to base their decisions on the performance of rendering an incomplete webpage depending on both random extension makers and random website creators.
> Note that last one: 1.8 MB memory consumption. And they're arguing that we need to be "setting up and tearing down this component as needed" to conserve that "valuable" 1.8 MB.
Ghostery is only one extension among them, and all the adblocking extensions in that performance study ran a pre-pruned set of EasyList rules when popular adblockers run more rules in practice.