fixed elements make firefox slow

[Victor Osadci]

Binary package hint: xulrunner

Gecko apps are very slow at scrolling when the page contains a fixed element in rapport to the canvas - ex: CSS "position: fixed;" .

An example is Gmail, which puts name tags fixed at the bottom right of the browser for discussions.
Also look at http://www.w3.org/TR/css-mobile/ , it has a fixed image at the top left.

[Alex Fraser (alex-phatcore)]

I can confirm this with gmail: scrolling when a fixed element is on the page seems much slower than it was in firefox 2.

I'm using fglrx on a Radeon Mobility X1400. Compiz is not enabled. Versions:
firefox-3.0: 3.0~b4+nobinonly-0ubuntu1
xorg-driver-fglrx: 1:7.1.0-8-3+2.6.24.11-12.31
libcairo2: 1.5.14-0ubuntu2
libgtk2.0-0: 2.12.9-2ubuntu2
xulrunner-1.9: 1.9~b4+nobinonly-0ubuntu1

[Alex Fraser (alex-phatcore)]

My own web site uses fixed elements and it doesn't seem any slower in firefox 3 than in firefox 2. Maybe it's the javascript in gmail that's executing slowly?

My site: http://localhost/phatcore/portfolio/ (top bar is fixed).

[Alex Fraser (alex-phatcore)]

A workaround seems to be to add this to the Device section of xorg.conf:
    Option "XAANoOffscreenPixmaps" "true"
After adding that option, scrolling in Gmail is much faster.

This is also a workaround for bug #182038.

[Alex Fraser (alex-phatcore)]

It seems I pasted the wrong link before. This is the real address of my site, with a page that exhibits slowdown (fixed by setting that option in xorg.conf): http://phatcore.com/projects/Track_And_Transform.php

[Alex Fraser (alex-phatcore)]

Sorry, phatcore.com no longer uses fixed elements so isn't suitable for testing.

[willem mulder (willemmulder)]

I can confirm this.
Especially with more than 1 fixed element, the scrolling gets slower and slower.
This by the way also goes for 'large' sites like http://tuaw.com which perform terrible when scrolling.

[willem mulder (willemmulder)]

@Alex:
Option "XAANoOffscreenPixmaps" "true" is default now, and doesn't help anything when you use EXA as rendering engine.
Also, it has nothing to do with firefox itself so if one could find the cause for the slow scrolling that would be great!

[Daniel T Chen (crimsun)]

Is this symptom still reproducible in 9.04?

[Pedro Villavicencio (pedro)]

We are closing this bug report because it lacks the information we need to investigate the problem, as described in the previous comments. Please reopen it if you can give us the missing information, and don't hesitate to submit bug reports in the future. To reopen the bug report you can click on the current status, under the Status column, and change the Status back to New. Thanks again!.