Sluggish scrolling and high cpu load with gif backgrounds




11 years ago
9 years ago


(Reporter: Magnus Stålnacke, Unassigned)


1.8 Branch

Firefox Tracking Flags

(Not tracked)





11 years ago
User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20061201 Firefox/
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20061201 Firefox/

I have set up two test pages, one page with gif background images and one just like it using png-images: 

The gif page can get very sluggish to scroll, causing 100% CPU usage (i have a AMD 64 +3000). On the page using png background images this does not happen.

Reproducible: Always

Steps to Reproduce:
1. Open the page containing gif backgrounds.
2. Move around another window on top of the browser, could be the "Page info" properties window or a terminal, whatever.
3. Now try to scroll the page.
Actual Results:  
The page scroll becomes very jerky and sluggish, when scrolling with the mouse wheel the page continues to scroll for quite some time, until the CPU comes off 100% load.

Expected Results:  
Expected results would be the same as the testpage with png background images. Normal scrolling and normal CPU load.

This problem came up on a fairly large swedish community site (, as of today the problem is still there, but now when i discovered that the problem goes away by converting backgrund images from gif to png, i expect them to change the site. So i made the test pages for you all to be able to reproduce the problem. On the problem is much more severe than my testpages, since that site is a quite heavy site with a lots of graphics like photos (it is a photo community), and complex menus and so on. In their forum a lot of Mozilla, Firefox and Seamonkey users complained about jerky scrolling, all of those users was on the Linux platform, especially Ubuntu users seemed to have the worst problems (could be a heavy desktop). So this bug seem to affect a lot of different versions and setups. But Mozilla based browsers on the windows platform did not report any problems.

Comment 1

11 years ago
The second step to reproduce is not allways necessary. Sometimes the bad scrolling is there from start, it seem like the odds for good scrolling at first visit is better with a newly restarted browser.

Comment 2

11 years ago
it sounds like you're seeing bug 255703.  What video card / driver are you using?

Comment 3

11 years ago
I have nvidia (the nv X-driver), and i do not experience problems with the testcases in bug 255703.

Comment 4

11 years ago
I can confirm this for a very similar machine.
CPU load increases from under 5% to about 50%, which is quite unusual on this box. To give you a feeling, that's in the same order of magnitude like google earth in flight simulator mode, in fullscreen 1600x1200, flying highspeed through the Grand Canyon.
And also confirmed, the 255703 example works completely ok here.

AMD Athlon 64 X2 (2x2Ghz), 3G, nVidia GeForce 7300 GT. 
# Kernel: Linux 2.6.24-rc8-amd64 (custom)
# Debian GNU/Linux lenny/sid
# Installed:
libc6   2.7-6
libc6-dev       2.7-6
libc6-i386      2.7-6
libglib-perl    1:1.161-1
libglib1.2ldbl  1.2.10-19
libglib2.0-0    2.14.5-2
nvidia-glx	169.07-2
nvidia-glx-ia32	169.07-2
nvidia-kernel-2.6.22-2-amd64	100.14.19-1+2.6.22-4
nvidia-kernel-2.6.22-3-amd64	100.14.19-1+2.6.22-5
nvidia-kernel-2.6.24-rc8-amd64	169.07-2+2.6.24~rc8-1~experimental.2~snapshot.10165
nvidia-kernel-common	20051028+1-0.1
nvidia-kernel-source	169.07-2
nvidia-settings	1.0+20070502-1
x11-xserver-utils       7.3+2
xserver-xorg    1:7.3+10
xserver-xorg-core       2:1.4.1~git20080118-1
xutils	1:7.3+10
xutils-dev	1:7.2.ds2-1
libx11-6	2:1.0.3-7
libx11-data	2:1.0.3-7
libjpeg-progs	6b-14
libjpeg62	6b-14
libpng12-0	1.2.15~beta5-3
libtiff4	3.8.2-7
libfreetype6	2.3.5-1+b1
libxrender1	1:0.9.4-1
libgtk2-perl	1:1.140-1
libgtk2.0-0	2.12.5-2
libgtk2.0-bin	2.12.5-2
libgtk2.0-common	2.12.5-2
libgtkhtml2-0	2.11.1-1
libgtkhtml3.8-15	3.12.3-2
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9pre) Gecko/2008042306 SeaMonkey/2.0a1pre

WFM (on single-CPU AMD Duron 1.2 GHz, openSUSE Linux 10.3, kernel, VGA card SIS 660, Xorg server "sis"). No significant difference in scrolling. (Both tescases, GIF and PNG, are somewhat more jerky than this Bugzilla page, both about equally, but nothing unbearable.) CPU use increase, if any, is hard to spot.

Note: My mouse has no wheel; using the scrollbar moves the other window to behind the browser window.

Magnus, Micha, are you still seeing this bug, and on which version(s) of SeaMonkey?

Comment 6

10 years ago
When i reported this i had Seamonkey 1.0.5 (spoofed to Firefox), now i have: 

Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20080313 SeaMonkey/1.1.9 

No difference. At first visit to the "gif page" it can go smoth, not allways. But as soon as i do something (move another window over) it gets extremly sluggish. 

How sluggish? 
If i scroll with the wheel down-up-down-up (about 6 click each) then the page do not stop moving (with 100% CPU AMD 64 +3000) for over 50 seconds! 

The "png page" is normal whatever i do.
Version: unspecified → SeaMonkey 1.1 Branch
Assignee: general → nobody
Component: General → Layout
Product: SeaMonkey → Core
QA Contact: general → layout
Version: SeaMonkey 1.1 Branch → 1.8 Branch

Comment 7

10 years ago
testcase is gone


9 years ago
Last Resolved: 9 years ago
Resolution: --- → INCOMPLETE
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