LitElement (grain-lit-element) Perf Demo

You can see the Result here:
Approach 1: Layered Custom Dom Elements
index-layered.html

Approach 2: Layered Dom (more in light dom)
index-light-dom.html

Approach 3: Flat Dom Tree
index-flat.html

And this is how it should look
https://claudiopro.github.io/react-fiber-vs-stack-demo/fiber.html

Known "Problem"?
Even with a flat dom structure handling so many levels of render instances of lit-html seems to be a performance problem.
Maybe there needs to be some shared knowledge? render priorities?