Comment by joeldrapper

It can be a mistake though to assume that the DOM hasn’t changed since it was rendered. Browser extensions, ad blockers and other JavaScript can modify the DOM.

I know it’s more expensive, but it’s like 1ms to render a document on the server and 3ms to morph it in the client. If you keep an SSE connection open, Brotli compression is very effective when you send almost the same HTML again and again.