There are good talks by the Chrome dev team from various GoogleIO's. CSS selectors used to have a lot of voodoo about them but no longer matter that much in terms of performance.
Try the blog of one Paul Irish and spread out from there.
> but no longer matter that much in terms of performance
That's not quite true. They matter enough that WebKit is implementing them incorrectly because they can't figure out how to make a correct implementation performant enough...
Try the blog of one Paul Irish and spread out from there.