Could you post a little more info? I am unclear whether you mean to say that this only happens when you open a second window or all the time.
bug 78695 seems to have a similar problem that was eventually attributed to using the forcastfox plugin. Could it possibly be related? ** Changed in: firefox (Ubuntu) Assignee: (unassigned) => ChrisBurgan Status: Unconfirmed => Needs Info -- firefox using over 90% of CPU https://launchpad.net/bugs/78786 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs