The extension Mark Selected Links As Visited 0.3 available at https://addons.mozilla.org/en-US/firefox/addon/mark-selected-links-as-visited hangs the browser about half the time I use it. Steps to reproduce: 1. install extension 2. visit https://www.reddit.com/ 3. click the button to mark all links on the page as visited Results: About half the time the whole browser hangs. Some of the time I can still switch tabs but none of them will load a web page. Expected results: links marked visited and no hanging.
This works fine for me, but of the main thread execution time that it causes, nearly all of it is in Places.
This needs a stack or a https://perf-html.io/ profile. Off-hand doesn't look like this should cause much main-htread stuff, it's just adding a visit. I wonder if something else is listening to history changes and slowing down everything, maybe another add-on or a test pilot.
I've been unable to reproduce this recently and it was intermittent before and now it seems gone.