Description of problem: Once I upgraded to Firefox 91, I observed much faster scroll speed, both with a mouse wheel and when using a touchpad. The scroll speed is now uncomfortably fast. With mouse wheel, I have to turn it slowly notch by notch, to be able to read comfortably. With touchpad, it's worse - I have to really carefully move the fingers very slowly, otherwise the acceleration kicks in and the whole page is scrolled off-screen, like as I had pressed PageDown. I didn't see this increased scroll speed in other applications or in Chromium, so it seemed Firefox-related. Today I had time to debug it, and I can confirm it is caused by Firefox 91. In particular, there are these important config options in about:config: mousewheel.system_scroll_override.enabled true mousewheel.system_scroll_override.horizontal.factor 200 mousewheel.system_scroll_override.vertical.factor 200 If I switch mousewheel.system_scroll_override.enabled to false, the speed is returned to the usual speed (Firefox 90 and before). Alternatively, I can keep it to true, but change the ".factor" lines to 100, and again, I'm back to usual (slower) speeds. It seems that "200" means 200%, i.e. it doubles the standard scroll speed. I downgraded to firefox-90.0.2-2.fc34, created a fresh profile, and the default values are different in this older version! See: mousewheel.system_scroll_override.enabled false mousewheel.system_scroll_override.horizontal.factor 200 mousewheel.system_scroll_override.vertical.factor 200 The observed scroll speed is as expected. After upgrading to firefox-91.0-1.fc34, the default value of mousewheel.system_scroll_override.enabled is changed from false to true, and scroll speed is doubled. To test the scroll speed, I used the following page: https://fedoraproject.org/wiki/Communicating_and_getting_help#User_Mailing_Lists With the standard scroll speed (FF 90) and 100% page zoom, each mouse wheel notch moves it by ~2.5 lines. With the increased scroll speed (FF 91), each notch moves it by ~5 lines. So this checks out, the scroll speed is doubled. (However, for me as a human, the change is most observable with larger scroll events, i.e. turning the wheel more as I'm used to, or moving the fingers on a touchpad, and suddenly the page "flies off-screen". I'm not sure if this change is intended by upstream Firefox, or if it can be caused somehow by Fedora integration. But the current behavior is a bug or a step in the wrong direction, in my eyes. Firefox now scrolls much faster than other apps/web browsers, and it's hard to use. Is the scroll override factor really supposed to be 200%? Version-Release number of selected component (if applicable): firefox-90.0.2-2.fc34 -- standard scroll speed firefox-91.0-1.fc34 -- doubled scroll speed How reproducible: always Steps to Reproduce: 1. install FF 89, create a fresh profile 2. test scrolling (mouse and touchpad) e.g. at https://fedoraproject.org/wiki/Communicating_and_getting_help#User_Mailing_Lists 3. upgrade to FF 90 4. test scrolling again, observe doubled scroll speed 5. open about:config and try to adjust mousewheel.system_scroll_override.* values Actual results: FF scrolls with double speed Expected results: FF scrolls with standard speed
I booted into Windows 10 to compare. The scroll override is also enabled on Windows: mousewheel.system_scroll_override.enabled true mousewheel.system_scroll_override.horizontal.factor 200 mousewheel.system_scroll_override.vertical.factor 200 I downgraded to FF 90 and interestingly, it is enabled there as well (using a fresh profile). When scrolling on my example page, each notch moves the page by ~4.5 lines, so a bit less than on Fedora, but very similar. When scrolling by larger amounts, though, FF on Windows behaves better - the page is not moved as much as on Fedora. E.g. when turning the wheel quickly by moving the finger all the way from up to bottom of the wheel, the page is scrolled more on Fedora then on Windows. I.e. I have a better scrolling experience on Windows. But unfortunately both systems (Fedora vs Windows) are installed on different PCs (but I'm using the same mouse), so the comparison might not be perfect. I also found this Reddit post where users complain about the same problem: https://www.reddit.com/r/firefox/comments/p2az3r/ff_91_messes_with_scrolling_by_default_why/ And that lead me to this Mozilla bugreport, which suggests this change was intentional in upstream Firefox :-( https://bugzilla.mozilla.org/show_bug.cgi?id=1715513
Oh, silly me! Anyway, can you just use your favorite values here? I haven't any strong preference here, let's see if there are more complains.
Would be great to get scroll speed values from Gtk / mutter but afaik there isn't such central settings for it.
> Anyway, can you just use your favorite values here? Sure. Now that I found out that it's the upstream default and not a Fedora-specific bug, I simply used the config options to override the behavior. But I'm still somewhat concerned about the default behavior, because especially the touchpad scrolling seems way too fast to me (and it seems a bit faster than on Windows, when comparing the scroll wheel in a very unscientific way), and most people will have no idea that they can configure it and how. But this is definitely very much opinion-based, so waiting if more people complain is reasonable (people on reddit complained already, though) :-)
(In reply to Martin Stransky from comment #3) > Would be great to get scroll speed values from Gtk / mutter but afaik there > isn't such central settings for it. Indeed there isn't, which is super annoying in other browsers like epiphany, where it's much too slow. (In Epiphany it takes me 6 full rotations to scroll _this_ bugzilla page) Anyway, "200" for me, on my hardware, is still too slow in Firefox. I strongly suspect it's hardware dependent, which is why I felt I needed to comment on this bug.
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