Why does Firefox4 for Mac feel less finished than for Windows or even Linux?
On Windows, tabs compress up into the title bar and you can utilize much more screen space for web pages. I wish this had made it into the Mac version. In addition, for mac, it just feels sluggish, laggy, and the browser itself hangs often. My experience with the other platform versions on the same computer is much better. It just feels like the mac version is still beta6.
Todas as respostas (2)
The Firefox button is only available on Windows and Linux and shows when the Menu bar is hidden. On Mac the menu bar is maintained by the Mac OS and not by Firefox and the Menu bar is always visible and can't be hidden, so there is no need for such a menu button.
Create a new profile as a test to check if your current profile is causing the problems.
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If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)
See:
... not once did I say anything about the menu button