Writing straight to the DOM is pretty fast - faster than a high-speed internet connection. It's the core idea behind a side project - write webpages in JSON, and have a small Javascript engine add these to the DOM.

It still has some bugs, but when it works, it's faster than calling the server for each page. This is because the entire site is loaded into the browser, and each page is deleted and rebuilt when a link is clicked. https://www.sparational.com