The Labproof over claims.
Proof over claims. Every number below is measured live on this page, in your browser. Not screenshotted from a framework's documentation.
Core Web Vitals captured from this very page while you read it.
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0 KB
good
The counter ticks up only when you interact with a module below.
Live Patch Grid
400-node fine-grained reactivity, head to head with a simulated VDOM re-render.
One interaction, one node. The grid stays responsive while the patch counter climbs.
Why it matters
In a VDOM world, one hover reconciles all 400 nodes. Here it touches exactly one. The same reason this page ships almost no JavaScript.
Glide the cursor. Qwik tracks reads through proxies and patches only the cell you touched.
Animation Bench A/B
Compositor-thread vs main-thread animation, running side by side.
Why it matters
Animating transform and opacity on the compositor thread is how interfaces stay responsive under load. That is also how I debug jank when a client reports it.
Both engines run 350 particles. Only one of them can starve the main thread.
Deferred Compute
Heavy logic that costs nothing until it is invoked.
Heavy chunk awaiting request
This module's JavaScript has not been downloaded yet. Activate it and watch the network.
This page (measured)
Why it matters
This is why pages I build can render in under a second even with heavy logic. The heavy code simply is not on the page until it must be.
A Mandelbrot renderer runs inside a Web Worker. Its chunk is requested only when you press the button.
Code Review Arena
A component generated by an AI model, with six production bugs hiding in it. Find them, then read my review.
Prompt: "Build a searchable product table for 10,000 rows." This is the unfiltered result.
import { useState } from "react"; const ProductRow = ({ product, i }) => { return ( <tr key={i}> <td>{product.name}</td> <td>{product.sku}</td> <td>{product.price}</td> <td>{product.stock}</td> <td> <button className="icon-btn" aria-label="Edit" onClick={() => editProduct(product)} /> </td> </tr> ); }; export default function ProductTable() { const [query, setQuery] = useState(""); const [products, setProducts] = useState([]); const filtered = products.filter((p) => p.name.toLowerCase().includes(query.toLowerCase()) ); const search = (value) => { setQuery(value); fetch("/api/products?q=" + value) .then((res) => res.json()) .then(setProducts); }; return ( <div className="table-wrap"> <input placeholder="Search products..." value={query} onChange={(e) => search(e.target.value)} /> <p>{filtered.length} results</p> <table> <tbody> {filtered.map((product, i) => ( <ProductRow key={i} product={product} i={i} /> ))} </tbody> </table> </div> ); }
What did you spot?
Why it matters
Generating code is commoditised. Reviewing it (performance, accessibility, edge cases) is the job.
Every fix below is the kind of comment a senior engineer leaves in a pull request.
Bundle Budget
What this page really shipped. Measured from network, not estimated.
This page (measured)
0 KBClassic SPA baseline
Public numbers from framework documentation, not measured here.
A classic SPA ships its framework up front, about 62 KB gzipped before any interaction. This page ships its application code only when you interact.
Why it matters
Every kilobyte of JavaScript is parse cost on someone's phone. Budgets turn that intuition into a number.
The resource list updates live as chunks load.