high cpu when viewing page containing animated gif

[svenw]

cpu usage goes up to around 25% on a page containing animated gifs (smileys)

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: firefox 10.0.2+build1-0ubuntu0.11.10.1
ProcVersionSignature: Ubuntu 3.0.0-16.29-generic-pae 3.0.20
Uname: Linux 3.0.0-16-generic-pae i686
AddonCompatCheckDisabled: False
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 1.23-0ubuntu4
Architecture: i386
ArecordDevices:
 **** Liste der Hardware-Geräte (CAPTURE) ****
 Karte 0: Intel [HDA Intel], Gerät 0: CONEXANT Analog [CONEXANT Analog]
   Sub-Geräte: 1/1
   Sub-Gerät #0: subdevice #0
AudioDevicesInUse:
 BEN. PID ZUGR. BEFEHL
 /dev/snd/controlC0: sven 2758 F.... pulseaudio
BuildID: 20120216101208
CRDA: Error: [Errno 2] Datei oder Verzeichnis nicht gefunden
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xfc620000 irq 48'
   Mixer name : 'Conexant CX20561 (Hermosa)'
   Components : 'HDA:14f15051,17aa2100,00100000'
   Controls : 17
   Simple ctrls : 9
Card29.Amixer.info:
 Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw 7VHT16WW-1.06'
   Mixer name : 'ThinkPad EC 7VHT16WW-1.06'
   Components : ''
   Controls : 1
   Simple ctrls : 1
Card29.Amixer.values:
 Simple mixer control 'Console',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
Channel: release
Date: Wed Mar 14 00:47:42 2012
ForcedLayersAccel: False
IncompatibleExtensions:
 Bindwood - <email address hidden>, Version=1.99.0, minVersion=3.5, maxVersion=9.0.*, Location=app-system-share, Type=extension, Active=Yes
 FireHbbTV - <email address hidden>, Version=1.0.14, minVersion=7.0, maxVersion=8.*, Location=app-profile, Type=extension, Active=Yes
 FlashGot - ID={19503e42-ca3c-4c27-b1e2-9cdb2170ee34}, Version=1.4, minVersion=1.9a3, maxVersion=1.9.*, Location=app-profile, Type=extension, Active=Yes
 NoScript - ID={73a6fe31-595d-460b-a920-fcc0f8843232}, Version=2.3.4, minVersion=1.9a2, maxVersion=1.9.6, Location=app-profile, Type=extension, Active=Yes
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427)
Profiles: Profile0 (Default) - LastVersion=10.0.2/20120216101208 (Running)
RunningIncompatibleAddons: True
SourcePackage: firefox
UpgradeStatus: Upgraded to oneiric on 2011-12-28 (76 days ago)
UserJS: plugin.expose_full_path - true
dmi.bios.date: 12/03/2010
dmi.bios.vendor: LENOVO
dmi.bios.version: 6FET87WW (3.17 )
dmi.board.name: 40623CG
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6FET87WW(3.17):bd12/03/2010:svnLENOVO:pn40623CG:pvrThinkPadW500:rvnLENOVO:rn40623CG:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 40623CG
dmi.product.version: ThinkPad W500
dmi.sys.vendor: LENOVO

[Michael Lynch (mlynchiii06)]

Reproduced by visiting http://senorgif.memebase.com/ and watching the system monitor. CPU shot up from 5% to 35% on bot cpus.

[svenw (svenw1973-launchpad)]

Just verified the problem exists with all extensions disabled. compared with chromium-browser, that stays far below 10% most the time, the firefox behavior is in-acceptable.

[svenw (svenw1973-launchpad)]

Is there any chance to get a fix for this bug?