Thanks for your reply. Closing as "Invalid" as cause of issue never confirmed.
** Changed in: firefox (Ubuntu) Status: Incomplete => Invalid -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to firefox in Ubuntu. https://bugs.launchpad.net/bugs/1711261 Title: firefox unacceptably slow Status in firefox package in Ubuntu: Invalid Bug description: firefox version 55.0.1 slow in loading pages slow in responding to input window darkens repeatedly xorg uses 15% cpu I will use chromium until this has been fixed ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: firefox 55.0.1+build2-0ubuntu0.16.04.2 ProcVersionSignature: Ubuntu 4.4.0-91.114-generic 4.4.76 Uname: Linux 4.4.0-91-generic x86_64 AddonCompatCheckDisabled: False ApportVersion: 2.20.1-0ubuntu2.10 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: humphrey 2246 F.... pulseaudio /dev/snd/controlC1: humphrey 2246 F.... pulseaudio BuildID: 20170814194055 Channel: Unavailable CurrentDesktop: Unity Date: Thu Aug 17 10:46:50 2017 ExecutablePath: /usr/lib/firefox/firefox Extensions: extensions.sqlite corrupt or missing ForcedLayersAccel: False IfupdownConfig: # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite) InstallationDate: Installed on 2017-07-27 (20 days ago) InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719) IpRoute: default via 192.168.0.1 dev enp4s0 proto static metric 100 169.254.0.0/16 dev enp4s0 scope link metric 1000 192.168.0.0/24 dev enp4s0 proto kernel scope link src 192.168.0.101 metric 100 IwConfig: lo no wireless extensions. enp4s0 no wireless extensions. Locales: extensions.sqlite corrupt or missing MostRecentCrashID: bp-75100bdc-c718-4fb8-a6e4-03b672170204 Plugins: Shockwave Flash - /usr/lib/flashplugin-installer/libflashplayer.so PrefSources: prefs.js Profiles: Profile0 (Default) - LastVersion=55.0.1/20170814194055 (In use) RfKill: RunningIncompatibleAddons: False SourcePackage: firefox Themes: extensions.sqlite corrupt or missing UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 06/22/2010 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.3.0 dmi.board.name: 0N185P dmi.board.vendor: Dell Inc. dmi.board.version: A02 dmi.chassis.type: 3 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.3.0:bd06/22/2010:svnDellInc.:pnVostro420Series:pvr:rvnDellInc.:rn0N185P:rvrA02:cvnDellInc.:ct3:cvr: dmi.product.name: Vostro 420 Series dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1711261/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp