There are reports on a number of support channels that the latest update of adblock plus 2.9, released at https://addons.mozilla.org/firefox/addon/adblock-plus/versions/?page=1#version-2.9 on may 24th, would cause serious performance degradation for some users. some references: * latest reviews at https://addons.mozilla.org/de/firefox/addon/adblock-plus/reviews/ * https://issues.adblockplus.org/ticket/5284 * https://www.reddit.com/r/firefox/comments/6ep1es/firefox_consuming_far_too_much_memory_buzzing_and/ * https://www.reddit.com/r/firefox/comments/6ee2b5/firefox_performance_drop/di9vnr4/ * https://www.camp-firefox.de/forum/viewtopic.php?f=1&t=120799

This is the result of a conversation we had on IRC noticing a sharp uptick in performance issues related to ABP (mine from reddit, philipp's from other venues). I also made this reddit post attempting to solicit additional testimonials from users. https://www.reddit.com/r/firefox/comments/6esz0r/is_anyone_experiencing_poor_performance_from/

At least bug 1362779 indicates two issues: 1) Saving Adblock Plus data being very slow (not great but normally not critical either). 2) Adblock Plus data being saved regularly for unknown reasons. If somebody experiencing this issue could create a performance profile and link to it here (see https://perf-html.io/ for instructions), that would be very helpful. At the very least, I could tell whether it is still the same issue or something different.

The performance log I got for this issue indicates bug 1320186 as one major contributing factor to the first part, saving to browser.storage.local is rather slow.

I will be implementing https://issues.adblockplus.org/ticket/5298 as a work-around. While this won't make saving data any faster, it will make sure that this is no longer necessary most of the time.

(In reply to Wladimir Palant from comment #2) > At least bug 1362779 indicates two issues: > > 1) Saving Adblock Plus data being very slow (not great but normally not > critical either). > 2) Adblock Plus data being saved regularly for unknown reasons. > > If somebody experiencing this issue could create a performance profile and > link to it here (see https://perf-html.io/ for instructions), that would be > very helpful. At the very least, I could tell whether it is still the same > issue or something different. See https://bugzilla.mozilla.org/show_bug.cgi?id=1368119#c3 for a profile.

Yes, bug 1368119 comment 3 is the same issue - very inefficient I/O. If you look at the main thread, you can see jsonStringify (from browser.storage.local implementation) taking more than 3 seconds in that profile. Adblock Plus 2.9.1 has just been released (pending approval by AMO), it has a work-around for this issue - Adblock Plus will no longer save its data as frequently.

I've just wanted to add that I've been experiencing the issue too. Disabling filter hit counts has helped much, greatly for browsing webpages, which is now normal in terms of speed (as if there was no issue). And it has helped medium for the performance of reading/saving/maintentaining Adblock Plus filters in the filters settings window, and "medium" means that there still are medium (no so big as before) UI janks in filters settings window, when maintentaining/doing various mouse actions/clicking/scrolling on the filters lists.