This wouldn't be the first time Apple's had a perf/polish focused release. For example Snow Leopard had almost no major features and was mainly perf and polish over Leopard.
Isn't Snow Leopard a complete myth? Back then they told to the public, that this is only a polish release, but they introduced the built-in anti virus solution, a complete rewritten Finder and QuickTime for example.
I remember that Snow Leo had lots of bugs in it's .0 release, it was only stable after some updates like every other OSX version.