[GhotiFish]

I know what you're saying, but think about things like jquery that every site uses. It's reasonable to source it remotely because everyone has it cached. Unless you had some content ID system in the browsers to pull locally sourced scripts up, we'd lose that instant CDN effect.

That said. It's hard to compare the benefits of that to the cost of the nonsense in OP's story. For every 50ms we've gained from cached jquery we've lost 3s to stupid advertising.

[clarry]

My experience (as a uMatrix user -- I get to manually whitelist domains all the time) is that most sites host their own copy of jquery anyway. And the sites that download scripts from external domains are usually the worst offenders -- they download a crapton of things from external domains, definitely not in my cache. As in they probably couldn't care less about performance. Name resolution often takes longer than it would take to serve these request first hand.