Using class names instead of attributes would make scoped styles faster

[esprehn]

Vue.js version

2.0.2

Vue per the docs is using a generated attribute names for scoped styles, for example it turns <style scoped> selectors from .a:hover into .a[vue-1]:hover. Matching and tracking the invalidation of attribute selectors is slow though, and you'd get much better RecalcStyle (see Chrome devtools timeline) performance if you use a generated class name like .a.vue-scope-1:hover {}

[fnlctrl]

Scoped style isn't vue's feature, please open an issue in the vue-loader repo instead, thanks!