If I open too many tabs in Firefox, it becomes extremely slow, sometimes too slow to be usable.  If I terminate it when it's slow, very frequently KDE's Plasma Workspace (shell) crashes; fortunately Plasma Workspace always restarts quickly.  The bug can't be reported by gnome-abrt, since the memory dump is too large.  Has anyone else seen this?

I would like to report this as a bug, but I'm not sure which bugzilla to report it to.