I am on OSX 10.8.2 and Firefox 17.0.1 - the base fonts of Firefox window and the page rendered by FF are very very bad and not smooth like other applications.
Check the grainyness of the entire FF UI elements, any fix for this ?
I think that the issue is due to the fact that Firefox's fonts do not scale up well in higher resolutions, and thanks to the "Retina display" on Macs which have a far larger resolution than what is considered to be normal, the fonts are looking blurry.
According to this bug, support for Retina display is coming to Firefox in version 18. Version 18 is released sometime in the the first week of New Year 2013. If you want to try this early, you can get a Firefox Beta build (version 18) which is released and updates features earlier than the normal release. You can get Firefox Beta here (your settings/history/cookies/etc. should be unaffected).
HHmmmm.. is the screen set to its native resolution ?
also, for web page content, a plugin for the 'Stylish' extension called 'Safari font rendering' forces Firefox to anti-alias fonts much nicer .. but it wont do much for the menu bars i'm afraid.