Closed Bug 530861 Opened 15 years ago Closed 10 years ago

position:fixed element causes choppy/slow scrolling / high cpu usage

Categories

(Core :: General, defect)

All
Windows XP
defect
Not set
normal

Tracking

()

RESOLVED WORKSFORME

People

(Reporter: jacob, Unassigned)

References

()

Details

(Keywords: regression)

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5

Scrolling is slow.

Hiding the anchor located by $("fdbk_tab") causes scrolling to go to normal speed.

Reproducible: Always

Steps to Reproduce:
1.visit url
2.scroll --> slow
3.javascript:$("fdbk_tab").hide();undef
4.scroll --> smooth
Actual Results:  
firefox.exe hogs a processor core while I scroll.

Expected Results:  
Don't use so much processor :)

* No plugins enabled
* Happens both with and without smooth scrolling
* Core2 6700 @ 2.66GHz, 4GB RAM
Hello!
I experience this bug too.

1. Visit this url: http://client.starchat.ee/987hjky4/thus.html
2. Click on button "Save". No matter which one. 
3. You will see that div box on left bottom corner appears. While it is there try to scroll the page - you will notice that page lags when you scroll it while the div is visible on bottom left corner. After it is gone, the scrolling is working smooth without any problems.
Forgot to mention:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)
Check also bug 90198 attachment 90636 [details].
And compare the cpu usage with attachment 90639 [details].

Reproduced with latest trunk.
Keywords: regression
See Also: → 201307
Blocks: 579794
Status: UNCONFIRMED → NEW
Ever confirmed: true
Hardware: x86_64 → All
Summary: position:fixed element causes choppy scrolling → position:fixed element causes choppy/slow scrolling / high cpu usage
Version: unspecified → Trunk
https://bug90198.bugzilla.mozilla.org/attachment.cgi?id=90636 doesn't use position:fixed.

Paint flashing shows that we don't do unnecessary repainting while scrolling http://www.flightcaster.com/faq. http://client.starchat.ee/987hjky4/thus.html is gone.
Status: NEW → RESOLVED
Closed: 10 years ago
Resolution: --- → FIXED
Resolution: FIXED → WORKSFORME
This is still an issue for me. 

Specifically, at lucidpress.com, when editing a document if I add a scrolling area and then double click on that scrolling area, then scrolling is painfully slow. In this case there are multiple elements with position:fixed, as well as multiple canvases. (one of which is position:fixed).

Disabling smooth scrolling in the preferences fixes the problem, however, I can't really require all of our users to disable smooth scrolling on their browsers. This is only a problem on Firefox.
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