455667 - regression: FF3 scrolls much slower than FF2

Status: RESOLVED DUPLICATE of bug 201307

(Firefox :: General, defect)

Description

[Kevin Hunter]

User-Agent:       Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.1) Gecko/2008072820 Firefox/3.0.1
Build Identifier: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.1) Gecko/2008072820 Firefox/3.0.1

For larger pages, the scroll performance of FF3 is considerably slower than that of FF2.  Slashdot news comments are good pages to highlight the problem.

This is much further highlighted by using the mouse wheel, or side-of-touchpad to scroll the page.  I'm not sure why.

Reproducible: Always

Steps to Reproduce:
1. Start firefox in safe mode ( firefox -no-remote -safe-mode )
2. Go to http://news.slashdot.org/article.pl?sid=08/09/16/1654217
3. Scroll up and down with mouse wheel or side-of-touchpad
Actual Results:  
Page scrolls up and down with a very noticeable lag and delay.

Expected Results:  
Scrolling should be near instantaneous.

I should not be able to quickly move my finger up and down the side of touch pad a few times, let go, and watch the page continue to scroll up and down for a few seconds.

I can confirm this performance regression with Ubuntu's version of FF2 and FF3, as well as a fresh download of Firefox directly from mozilla.org.

$ uname -a
Linux hani 2.6.24-19-generic #1 SMP Wed Aug 20 17:53:40 UTC 2008 x86_64 GNU/Linux

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 8.04.1
Release:	8.04
Codename:	hardy

I'm not sure if these bugs are related: <a href='https://bugzilla.mozilla.org/show_bug.cgi?id=372039' title='[Fx3] Slow and laggy scrolling with fixed background, high CPU usage'>372039</a>, <a href='https://bugzilla.mozilla.org/show_bug.cgi?id=443766' title='css background: fixed; causes slow scrolling AND flash/script elements to lag'>443766</a>

Comment 1

[Kevin Hunter]

Learning bugzilla.  Could have done this instead.  Possibly related bugs:

Bug 372039
Bug 443766

Comment 2

[Mardeg]

line 156 in http://images.slashdot.org/core-tidied.css?T_2_5_0_220 has:
#modal_box{position:fixed;width:50%;z-index:1000001;border:4px solid #222;overflow:hidden;background:#fff;height:65%;padding-bottom:2.6em;margin:10% 25%;}

This may be a dupe of bug 201307