Using Firefox 29.0 on the recently upgraded Ubuntu 13.10 results in high CPU load. By running top on the commandline I can see that the high CPU load goes to the following processes:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3540 dupo 20 0 236m 175m 2768 R 28.5 5.8 111:21.84 hud-service
32469 dupo 20 0 1051m 427m 50m S 13.3 14.1 9:38.83 firefox
3809 dupo 20 0 424m 65m 16m R 3.6 2.2 33:27.02 compiz
3503 dupo 20 0 6904 3156 904 S 1.7 0.1 7:00.64 dbus-daemon
3549 dupo 20 0 213m 86m 9856 S 1.7 2.8 23:36.36 unity-panel-ser
3863 dupo 20 0 53516 5168 4024 S 1.7 0.2 11:34.61 indicator-multi
1725 root 20 0 439m 96m 64m S 1.3 3.2 57:24.35 Xorg
This occupies constantly at least one quarter of the CPU capacity of the PC (2 CPUs). It gets worse while browsing, particularly when it comes to pages with a lot of background JSON, such as Fbook. After some time the computer gets too slow and occasionally irresponsive, preventing me from typing in a website text field or so. In that case, the only solution is restarting Firefox.
