Many of the tips in this article are tiny micro-optimizations, one thing to keep in mind when going overboard with optimizing. You should never sacrifice maintainability or extensibility for optimization experiments. Consider this article more like an academic exercise rather than real-life optimization tips.
It should also be noted that if you need to speed up your web site, don’t bother with CSS optimization. There are much better places to focus your attention to. The point of this and all optimization articles is to consider an optimization in context, not in isolation…