PUBLIC MARKS with tags Dragonfly & performance

As a real world example of how big the impact can be on performance, I made a test with the full HTML5 specification downloaded locally and ran the profiler. I noticed few of the most expensive selectors had ":link" and ":visited". I changed these to instead be "a:link" or "a:visited" (in this case they were equivalent in terms of which elements matched). This trivial change makes the engine use a cache, and bought the selector matching time down from about 14 seconds to about 11 seconds.