I would like a feature that is site specific. Sites use ads from other sites, and sometimes the ad is not loading properly or something, which slows things down. I don't see any ad anywhere, the site just loads something from an other site for some reason, still.
For example I go to site 1 and I see it loading something from site 2, not ad, but something. Well, I don't want to block that site 2, because it happens to be a site, that I also visit. So I would like to block site 2 only when I am in site 1.