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Comment by karon | Hacker News Reader

How is that even possible? Firefox with blocker uses less RAM than without? Does it block elements from issuing requests?

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One would expect any ad blocker that actually blocks ads to reduce memory consumption significantly. Ad blockers that merely hide ads exist and have succeeded in earning reputations as ad blockers despite only doing half the job.

True, but when I uninstalled Adblock Edge, I gained almost a gigabyte of memory in Firefox. (I'm now using Ghostery to block ads. It isn't as effective but I'd rather reduce the memory footprint.)

Alas, it's not that simple. See these bugs about AdBlock Plus's effects on Firefox's memory usage:

https://bugzilla.mozilla.org/show_bug.cgi?id=988266 https://bugzilla.mozilla.org/show_bug.cgi?id=1001426

That second bug is lacking in technical details, but the first one is clearly about the memory consumption of the CSS rules used to hide elements. If you only use rules that match URIs instead and not element ids, ABP is extremely efficient.

It's worth remembering that ABP only implemented the element-hiding feature so that things like inline text ads could be blocked, but now the popular rule lists are using a large number of broad rules to hide all kinds of elements, many of which could probably have been effectively blocked with URI-matching rules.

Additionally, it's very unfair to the ABP devs to be criticizing the performance or memory usage of ABP when the problem is really the memory usage of EasyList. Using a more restrained and targeted rule list makes the problems go away.

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