Hockenberry feels that though content blocking has helped in reducing the resource abuse and hence providing better performance and better battery life, there are few downsides of using content blockers. His bug report said, “it’s hurting many smaller sites that rely on advertising to keep the lights on. More and more of these sites are pleading to disable content blockers.” This results in collateral damage to smaller sites.
As an end result, he believes that we can allow sites to show as many advertisements as they want, but keeping the overall size under a fixed amount. He believes that we can also ask users for permission by adding a simple dialog box, for example, “The site example.com uses 5 MB of scripting. Allow it?”
“CPU usage allows an initial burst, but after a few seconds dial down to max ~0.5% of CPU, with additional bursts allowed after any user interaction like click or keyboard)
Number of HTTP requests (again, initial bursts allowed and in response to user interaction, but radically delay/queue requests for the sites that try to load a new ad every second even after the page has been loaded for 10 minutes)
Memory usage (probably the hardest one to get right though)”
Another user adds, “With that said, I do hope we’re able to figure out how to treat web “sites” and web “apps” differently – for the former, I want as little JS as possible since that just gets in the way of content, but for the latter, the JS is necessary to get the app running, and I don’t mind if its a few megabytes in size.”
You can read the bug reported on WebKit Bugzilla.