398137 - OSX performance: scrolling is much smoother when the scrollbar is not seen

Status: RESOLVED WORKSFORME

(Core :: Widget: Cocoa, defect, P3)

Description

[Simon Strandman]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X; sv-SE; rv:1.9a9pre) Gecko/2007092704 Minefield/3.0a9pre
Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; sv-SE; rv:1.9a9pre) Gecko/2007092704 Minefield/3.0a9pre

I've found a weird problem with FF3 nightly builds on OSX. Scrolling is quite laggy on many pages with smooth scrolling turned on. It's not as bad as in FF2 but still. I've found a way to make it a lot smoother. Just move the window slightly to the right so that the scrollbar is outside the screen. Now scrolling becomes much smoother. It also works with horisontal scrollbars. This suggest that it's not the scrolling on the pages that is slow but rather the scrolbars. This does not work with FF2 btw.

Reproducible: Always

Steps to Reproduce:
1. Install FF3 on Mac OS X.
2. Enable smooth scroll.
3. Visit some random pages and notice the slowness when scrolling.
4. Move the window slightly to the right so that the scrollbar is outside the screen.
5. Visit the same pages again, now scrolling is a lot smoother.

Comment 1

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

I have no idea why this was minus'd.

Comment 2

[Simon Strandman]

The fix for bug #417612 improved this slightly, but scrolling is still a lot smoother when the scrollbar is outside the screen. Also this is mostly a problem when the window is maximized.

Reopening.

Comment 3

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Josh, I don't think this is a 1.9 blocker -- there's probably some perf wins that can be had here, but drawing the scrollbar itself takes time.  I'm not even sure if this is gfx related, due to smoothscroll needing to be enabled.  Let me know if you disagree with the blocking-.

Comment 4

[Wayne Mery (:wsmwk)]

same as bug 504347?