Public bug reported: It's a bit fuzzy report, I have to admit, and more like a feeling, as I can't check it out too well, but I haven't experienced that in previous Ubuntu versions before upgrading to Wily.
I have firefox running with many tabs open. The CPU usage (without too much active pages, ie no videos etc) is about 10-30% at max. If I lock my computer I always hear the fan of the notebook switches onto a higher speed, which disappears if I unlock the screen. It's a bit hard to check it out, if it's really because of firefox, as I can only use "top" if my desktop is unlocked of course, but I can still notice that CPU usage of firefox is still about decreasing after unlocking. ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: firefox 41.0.2+build2-0ubuntu1 ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3 Uname: Linux 4.2.0-16-generic i686 AddonCompatCheckDisabled: False ApportVersion: 2.19.1-0ubuntu3 Architecture: i386 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: lgb 2439 F.... pulseaudio BuildID: 20151016093451 Channel: Unavailable CurrentDesktop: Unity Date: Tue Oct 20 23:48:56 2015 DefaultProfilePlugins: IcedTea-Web Plugin (using IcedTea-Web 1.5.2 (1.5.2-1ubuntu2)) - /usr/lib/jvm/java-7-openjdk-i386/jre/lib/i386/IcedTeaPlugin.so (icedtea-7-plugin) Google Talk Plugin Video Renderer - /opt/google/talkplugin/libnpo1d.so (google-talkplugin) iTunes Application Detector - /usr/lib/mozilla/plugins/librhythmbox-itms-detection-plugin.so (rhythmbox-mozilla) Shockwave Flash - /usr/lib/flashplugin-installer/libflashplayer.so Google Talk Plugin - /opt/google/talkplugin/libnpgoogletalk.so (google-talkplugin) DefaultProfilePrefSources: prefs.js ForcedLayersAccel: False IfupdownConfig: auto lo iface lo inet loopback InstallationDate: Installed on 2012-03-03 (1326 days ago) InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1) MostRecentCrashID: bp-c1602958-abcf-49cb-af9c-c95172151003 Profile1Extensions: extensions.sqlite corrupt or missing Profile1IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite) Profile1Locales: extensions.sqlite corrupt or missing Profile1Plugins: IcedTea-Web Plugin (using IcedTea-Web 1.5.2 (1.5.2-1ubuntu2)) - /usr/lib/jvm/java-7-openjdk-i386/jre/lib/i386/IcedTeaPlugin.so (icedtea-7-plugin) Shockwave Flash - /usr/lib/flashplugin-installer/libflashplayer.so iTunes Application Detector - /usr/lib/mozilla/plugins/librhythmbox-itms-detection-plugin.so (rhythmbox-mozilla) Profile1PrefSources: prefs.js Profile1Themes: extensions.sqlite corrupt or missing Profiles: Profile0 (Default) - LastVersion=41.0.2/20151016093451 (In use) Profile1 - LastVersion=39.0a2/20150414004003 (Out of date) RelatedPackageVersions: icedtea-7-plugin 1.5.2-1ubuntu2 google-talkplugin 5.41.0.0-1 rhythmbox-mozilla 3.2.1-1ubuntu3 RfKill: 0: phy0: Wireless LAN Soft blocked: no Hard blocked: no RunningIncompatibleAddons: True SourcePackage: firefox UpgradeStatus: Upgraded to wily on 2015-10-18 (2 days ago) dmi.bios.date: 11/04/2011 dmi.bios.vendor: LENOVO dmi.bios.version: 8GET38WW (1.15 ) dmi.board.name: 5016NW6 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:bvr8GET38WW(1.15):bd11/04/2011:svnLENOVO:pn5016NW6:pvrThinkPadL520:rvnLENOVO:rn5016NW6:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.name: 5016NW6 dmi.product.version: ThinkPad L520 dmi.sys.vendor: LENOVO ** Affects: firefox (Ubuntu) Importance: Undecided Status: New ** Tags: apport-bug i386 wily -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1508219 Title: Possible high CPU usage by firefox while screen is locked To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1508219/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs