Let me clarify: the DOM is fast _at what it does_. But in order to truly serve things like web apps rather than documents it needs to have primitives like list virtualization. It doesn't, so people end up using needlessly complex JavaScript frameworks that drag down performance.
> But in order to truly serve things like web apps rather than documents it needs to have primitives like list virtualization.
Why not create a UI system, like X Window over the web (I know X can be done over the network) specifically for web apps? Solve the issue at the root and leave the DOM to documents.
Most web apps use it for what it wasn't meant to do, in an inefficient matter, with useless rerenders and overhead.