640663 - Smooth Srolling in Firefox makes no sense with Scrolling "with Inertia" on OS X

Status: RESOLVED WORKSFORME

(Firefox :: Untriaged, defect)

Description

[Johannes]

User-Agent:       Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0) Gecko/20100101 Firefox/4.0

Since Mac OS 10.6 (or so i believe), all Macbooks and their Touchpad come with a preference setting that's called Scrolling "with Inertia". It means that when you scroll with two fingers on the touchpad, and let go while still in motion, the scrolling will continue, but slowly decrease in speed until it stops. Like dragging something on a smooth surface, and then letting go, which results in the object stopping after a while due to friction.

With this enabled, it basically replaces any application-simulated smooth scrolling, like the one Firefox has. Not only does it make it obsolete in this case, having smooth scrolling enabled in Forefox unnecessarily decreases performance (noticably so) and leads to more jaggy scrolling, as it's basically "smoothed out" twice.

Therefore I think this feature should be disabled on recent Macbooks. Most users will have no idea about the fact that Firefox is actually performing much slower that it could on their Macbook. Or why it is performing slower than on other people's computers.

Reproducible: Always

Steps to Reproduce:
1. Steal a Macbook (optionally buy one or borrow from a friend)
2. Enable Inertia Scrolling (System Preferences > Trackpad)
3. Make sure Smooth Scrolling in Firefox is enabled (afaik it is by default)
4. Play around with it for a while, best on a long page like The Planet [1]
5. Disable Smooth Scrolling
6. Observe how much smoooother it is now and how much faster!
7. Open up your favorite coding environment and disable and remove this option for Macbooks in Firefox
8. Throw your hands up in the air and make some silly noise (like so [2]) because you made yet another end user happy

[1] http://planetkde.org/
[2] http://i624.photobucket.com/albums/tt322/McDeannaBanana/Funny%20Shit/Spongebobloololol.gif

Comment 1

[Florian Bender]

I can't seem to reproduce this on Fx 28 Aurora (through a subjective visual test). Is this still an issue for you? 

Would be great if somebody can profile this. Also, I don't really know where to put this, might be a Widget: Cocoa thing but IMO not simply a pref thingy.

Comment 2

[Johannes]

I can't reproduce the performance issue myself anymore. The "Scrolling with Inertia" setting has disappeared (because it's always turned on now) in OS X Mavericks or before that even. Disabling smooth scrolling in Firefox doesn't bring any noticeable performance increase anymore when scrolling using the Trackpad. I think this issue can be closed now. Maybe someone fixed it in the meantime?

Thanks for looking into this though :)