Why Marko Is Fast

You’ve now seen the machine from the inside — effects, the reactivity graph, two programs from one template, resumability. This lesson steps back and names why those pieces add up to a fast framework. There’s no exercise; read the page’s source on the right as you go — it’s a mostly-static page with a single interactive control, and it ships almost no JavaScript. That’s the whole thesis in miniature.

Targeted compilation

The compiler emits two programs from your one template — one for the server, one for the browser (you saw this in Two Programs from One Template). The server build renders straight to an HTML stream in a single pass: no virtual DOM, no intermediate tree, just string concatenation. Frameworks built on a virtual DOM must first build a tree in memory and then serialize it — two passes. Marko does one.

JS scales from zero

Because reactivity is resolved at compile time, the client build doesn’t ship a DOM representation or a diffing runtime. It ships only what actually changes: stateful values, event handlers and <script> effects, and a tree-shaken core runtime. Static content compiles to zero client JavaScript — even when it sits in the same template as interactive content. A page that’s 95% static ships the JS for the 5% that isn’t. (The next lesson digs into how fine-grained that splitting really is.)

First-class HTML streaming

Because the server renders in a single streaming pass, sending HTML as it’s produced is natural, not bolted on. <await> holds the stream at a slow section and flushes the rest immediately; the browser paints as chunks arrive. Marko has streamed HTML since 2013 — years ahead of most of the ecosystem. Part 11 is devoted to it.

Compile-time reactivity

Other frameworks discover what to update at runtime (re-run a component, diff the result). Marko works it out at compile time — the graph you met two lessons ago — so the browser does the minimum: touch exactly the nodes a changed signal feeds, nothing more.

Put together: small bundles, single-pass server renders, streaming by default, and surgical client updates. Not one trick — an architecture where the compiler carries the weight so your code, and your users’ browsers, don’t. For the deeper write-ups, see the docs’ Why Is Marko Fast and Targeted Compilation explanations.