12.10 Very high CPU load when using Firefox with Hud and Unity Panel

Very often, when using Firefox v23.0 with Ubuntu 12.10, suddenly I get high CPU load, spanning over my two CPU processors. The load keeps steady at 100-150% (two CPUs), practically preventing any further activity on the browser, even on the rest of the system.

After inspecting the processes running via top, I get high CPU usage for the hud service and the unity-panel-service, along with Firefox. After some minutes the load may go down, but starts again when I move to another page or tab.

If you manage to the the system responsive and close Firefox (or kill via a console) things get soon calmer. But the high CPU resumes if you launch Firefox again, even without restoring the previous session.

This issue exists for several years, also while using previous Ubuntu and Firefox versions. Somebody has suggested that this is due to the big number of bookmarks, which HUD tries to index every while and then. The trick back then, was to disable the Firefox Extension called "Global Menu". But since one of the latest updates, this Extension does not show up, which suggests that it might have been somehow integrated into Firefox. By disabling Global Menu you would loose the HUD functionaility, but you got some browsing stability.

I recently reset my Firefox profile to the default settings, which removed all other extensions but not the bookmarks.
I also tried to create an empty Firefox profile with absolutely no bookmarks. Indeed, I noticed that this profile runs smoothly, even when firing HUD.
With the current situation Firefox has become greatly unusable and I am considering migrating to another browser.

Could please somebody suggest a solution for this issue?