Maxed star unless someone finds something insane. The only factors that matter are the bridge timing (basically RNG in practice with a 1/8 success rate), when exactly Mario leaves the bridge (+ at what height), and when Mario ground-pounds. There are several combinations which will give 6"76, but none can go a frame lower.

Ultimately the star is bound by the bridge cycle as there's no way to get enough height to reach the top until it has risen far enough, and lava VS is the highest you can store, beating out even a triplejump. So to improve it someone would have to find a way to get higher VS on the bridge or jump significantly higher than a triplejump, and there aren't really any good options around as far as I can tell.

(Submitted in 2024 in an effort to make sure all my runs are on srcom)