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Ahmed Mahmoud
Ahmed Mahmoud

Posted on • Originally published at eng-ahmed.com

Signals vs React Compiler: The Fine-Grained Reactivity Showdown

#react #performance #webdev #javascript

Headline: Signals win on raw performance and mental clarity. React Compiler wins on ecosystem leverage and migration cost. For a greenfield app, signals are tempting; for a real product, ecosystem still wins.

For a decade the frontend community has chased the same goal: minimize unnecessary work. In 2026, two distinct answers reached production maturity at the same time — signals (Solid, Vue 4, Angular 20, Svelte 5) and the React Compiler. They solve the same problem from opposite directions.

The Problem Both Solve

The classic React mental model re-renders entire component trees when state changes, then relies on the developer to remember memo, useMemo, and useCallback to avoid waste. Most teams get this wrong in subtle ways and pay an interactivity tax — the INP score most apps fail.

Signals: Track at the Value Level

Signals are observable values. A component subscribes by reading the signal; when the signal changes, only that subscription re-runs. There is no virtual DOM diff for the unchanged parts.

// SolidJS
const [count, setCount] = createSignal(0);
<button onClick={() => setCount(c => c + 1)}>
  {count()} {/* only this text node updates */}
</button>
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Smaller runtimes, fewer hydration mismatches, and an authoring model where "what re-renders" is something you can read off the page rather than guess at.

React Compiler: Memoize Automatically

React's bet is different. Instead of changing the runtime, change what the developer writes. The compiler analyzes your component, identifies stable values, and inserts memoization at build time. You delete every useMemo you ever wrote.

function Cart({ items }) {
  const total = items.reduce((s, i) => s + i.price, 0);
  return <Total amount={total} />;
}
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The compiler caches total across renders when items is referentially stable.

Head to Head

On a synthetic counter benchmark, Solid is roughly 3× faster than React + Compiler. On a realistic 200-component dashboard rerender, the gap shrinks to ~1.4×. On a real product (the kind we ship at Devya Solutions), the gap was negligible after accounting for network and database latency.

The Ecosystem Cost

Signals require you to leave the React ecosystem. That means re-evaluating routing, data fetching, charts, design system, error monitoring, and the LLM coding assistant your team uses. Most LLMs in 2026 generate React idioms by default — the "invisible teammate" effect is real and meaningful.

Practical Advice

  • Greenfield, performance-critical, small team → Solid or Svelte 5
  • Greenfield, product velocity matters → React + Compiler
  • Existing React app → adopt the React Compiler this quarter. Free wins, no migration.
  • Want signal semantics inside React → look at @preact/signals-react for opt-in fine-grained state.

Closing Thought

The signals camp won the architectural argument; React won the distribution argument. In 2026, both are valid choices — and the right one depends more on team and tooling than on benchmarks.

For more frontend architecture writing, visit eng-ahmed.com or follow what we're building at Devya Solutions.

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