Open Bug 713220 Opened 11 years ago Updated 6 months ago

Page scrolling lag on heavy js site


(Firefox :: General, defect)

9 Branch
Windows 7





(Reporter: ahcheong, Unassigned)


(Whiteboard: [Snappy])


(1 file)

802.19 KB, application/octet-stream
User Agent: Mozilla/5.0 (Windows NT 6.1; rv:9.0.1) Gecko/20100101 Firefox/9.0.1
Build ID: 20111220165912

Steps to reproduce:


Actual results:

Scrolling very lag on the

Expected results:

Scrolling smoothly.
Do you have the new timeline interface activated in facebook ?
This is probably a dupe of bug 712883
i didn't enable timeline for my profile.
It happen in news feed page.

besides that, while playing flash movie in facebook or any website contains flash movie, flash movie is lag is compare to google chrome.

I think it is something related to javascript.

p/s: while happening any lag i found that cpu usage very high
Does the problem also occur in a Nightly build?
Summary: facebook scrolling lag → Page scrolling lag on heavy js site
I changes the summary..
Because I found that firefox facing scrolling lag in Gmail, Google Reader as well
I tried with nightly version (12a1), no much different.
lag on scrolling and lag while playing flash movie as well
See Bug 712883
I confirm. It is not only facebook problem. Firefox had the awesome scroll on Google Reader until google changed it's design. Now it's fully impossible to work with GReader with FX (I had to use external RSS reader).
Checked on Nightly UX 12.0a1. The same problem. Changing smooth scroll doesn't help.
Please confirm bug.
Enable Smooth Scrolling in GReader Settings (Experiments tab) doesn't work.
Nothing changed in 13.0a1. Please let me uninstall Chrome!!!
Yet Another Smooth Scrolling extension solve problem, but
is history already.
I agree. No changes even in version 21 :(
This bug blocks this: "Become a market leader in performance" (

Please confirm this bug and make smth.

P.S. Try GReader with Chromium if you think it's OK with FX.
Getting a profile using the builtin profiler in 21 might help diagnose this problem:
Whiteboard: [Snappy]
my profile in attach (if it can help).

I have: Firefox UX latest build, Windows 7 x86

Steps used to create profile:
1. start UX, login to GReader
2. Scroll 100 unread items

All add-ons and plugins were disabled (except Gecko Profiler 1.11.19, Flash 11.6.602.108 and Silverlight 5.1.10411.0)

3. Press 'Analyze'
4. Save profile to local file.
Thanks for the profile, mihal. For future reference, it's usually more convenient to analyze if you upload the profile and dump the link in the bug instead.
Severity: normal → S3
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