Dean Murphy does a comparison of iMore.com before and after iOS 9 content blocking was enabled.

With no content blocked, there are 38 3rd party scripts (scripts not hosted on the host domain) running when the homepage is opened, which takes a total of 11 seconds. Some of these scripts are hosted by companies I know, Google, Amazon, Twitter and lots from companies I don’t know. Most of which I assume are used to display adverts or track my activity, as the network activity was still active after a minute of leaving the page dormant. I decided to turn them all off all 3rd party scripts and see what would happen.

After turning off all 3rd party scripts, the homepage took 2 seconds to load, down from 11 seconds. Also, the network activity stopped as soon as the page loaded so it should be less strain on the battery.

Here’s iMore’s Rene Ritchie’s take:

To answer the obvious questions, yes. Everyone here and at our network, Mobile Nations, saw it. Everyone here and at our network were also well aware of it, and have been working for months already to improve it. That we haven’t made it further, faster is an indication of how hard it is when you’re talking about websites visited by tens of millions of people, and companies that employ more than a dozen writers. Of course, everyone here is going to continue working to find better, smarter ways of solving the problem, because that’s our jobs. I’m sure other large websites are doing likewise.

This is an interesting and non-trivial issue. If we completely block ads, the advertising revenue that pays folks who write for sites like iMore is impacted, if not eliminated. As nature abhors a vacuum, some other mechanism, immune to this type of ad-blocker, will no doubt rush to fill this void.