You appear to have been downvoted; while I don't know whether your potential solution is right or wrong your downvoters should have been polite enough to explain their reasoning.
> virtual DOM nodes for static areas of your markup
refers to React's virtual DOM implementation, not Ember's.
> I'm not familiar with Ember, but why not just store the constant value in a variable to solve this problem?
Ember is a complex framework. Suggesting a "solution" to challenges with an acknowledged lack of context, and adding "Simple", shows fairly poor attitude.
> I just stash large, static parts of the tree in variables and only rebuild vdom nodes for dynamic content
This sounds pretty much like what is already described in the PR.
Again, still confused, and still don't know what is being suggested.
yesterday, I got downvoted repeatedly for mentioning that I hadn't seen an IIS header in years. ¯\_(ツ)_/¯