Don't worry about the version number -- a higher number doesn't mean there's a ton of new features; it merely means 6 weeks has passed. Pretty soon, upgrade dialogs will be completely suppressed and it won't matter what version you're on (much like Chrome). I like the rapid release; it means as a developer I can play with new features much sooner.
Firefox is as fast or faster than any other browser (assuming you don't load it up with add-ons). [1] So it's not like everyone at Mozilla stopped programming and started focusing all their energy on merely incrementing the version number from 7 to 8.
I don't know why you're so worried -- version is just a number.
Actually there is a stable API that works much like Chrome's, it's called Jetpack [1], the problem is that most addons don't use it, in part because also like Chrome's, it's much more limited - the default JS API basically gives the addon access to the whole Firefox internals.
Firefox is as fast or faster than any other browser (assuming you don't load it up with add-ons). [1] So it's not like everyone at Mozilla stopped programming and started focusing all their energy on merely incrementing the version number from 7 to 8.
I don't know why you're so worried -- version is just a number.
[1] http://lifehacker.com/5844150/browser-speed-tests-firefox-7-...