The big restriction on that system was honestly memory, since the GameCube only had around 24MB of memory usable by the CPU. That's really what necessitated splitting up the Great Sea into chunks. Check the Chrome memory usage while that's loaded; guaranteed it'll be a bit higher.
Some actors have simulations (e.g. Beedle's boat) but not too many right now. Compare to Super Mario Galaxy or the Source Engine games where there's even a bit of interactivity.