This issue seems somehow related to #1710978. Deinstalling tlp (and associated programs) the issue disappears.
-- 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/1711382 Title: slow performance, high cpu load Status in firefox package in Ubuntu: New Bug description: After installing Firefox 55 the browser generates huge cpu load, startup is extremely slow (it takes > 10s for the taskbar to accept entries after launch (this is new to 55) Due to high cpu load the computer tends to overheat, ventilation jumps in making the machine extremely loud. Using Chromium does not show these symptoms (on the same page). --- LSB Ubuntu 17.04 (budgie desktop) firefox: Installed: 55.0.1+build2-0ubuntu0.17.04.2 Candidate: 55.0.1+build2-0ubuntu0.17.04.2 Version table: *** 55.0.1+build2-0ubuntu0.17.04.2 500 500 http://archive.ubuntu.com/ubuntu zesty-updates/main amd64 Packages 500 http://archive.ubuntu.com/ubuntu zesty-security/main amd64 Packages 100 /var/lib/dpkg/status 50.1.0+build2-0ubuntu1 500 500 http://archive.ubuntu.com/ubuntu zesty/main amd64 Packages ProblemType: Bug DistroRelease: Ubuntu 17.04 Package: firefox 55.0.1+build2-0ubuntu0.17.04.2 ProcVersionSignature: Ubuntu 4.10.0-32.36-generic 4.10.17 Uname: Linux 4.10.0-32-generic x86_64 NonfreeKernelModules: wl nvidia_uvm nvidia_drm nvidia_modeset nvidia ApportVersion: 2.20.4-0ubuntu4.5 Architecture: amd64 BuildID: 20170814193419 CurrentDesktop: Budgie:GNOME Date: Thu Aug 17 16:30:30 2017 InstallationDate: Installed on 2017-05-25 (83 days ago) InstallationMedia: Ubuntu-Budgie 17.04 "Zesty Zapus" - Release amd64 (20170412) SourcePackage: firefox UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1711382/+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