449998 - When there is a div with style position set to fixed, rendering while scrolling is hogging cpu

Status: RESOLVED DUPLICATE of bug 372039

(Firefox :: General, defect)

Description

[Hasan Ceylan]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.1) Gecko/2008071615 Fedora/3.0.1-1.fc9 Firefox/3.0.1
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.1) Gecko/2008071615 Fedora/3.0.1-1.fc9 Firefox/3.0.1

I am sure that this is caused by the fixed position style. 

Go to sample pages and turn the fixed on and off with firebıg to see the difference.

By the way this is only on linux, Windows version is fine. 
And I also tested the pages with safe mode | all extensions disabeled and javascript disabled.


Reproducible: Always

Steps to Reproduce:
1.Go to http://www.xwiki.org/xwiki/bin/view/Main/Download
2. scroll down observer CPU usage and visual rendering experience as you scroll
3. open firebug, go to style and block the position: fixed css element on div "actionmenu"
4. scroll to see the difference

5. Go to http://www.tuaw.com, and do the same experiment with the 'fixed' bit on the body background style
Actual Results:  
scrolling with the 'fixed' set, firefox tops up the cpu and scrolling looks bad and slow


Event on this bugzilla page you can try to set the position: fixed for the header div to see the same result.

Although I think this is a major problem, I'll leave it up to QA to decide on the serverity.

Regards,
Hasan Ceylan