SolidJS vs Svelte 5 vs React: Reactivity 2026

Fine-grained reactivity has become the defining technical conversation in frontend development. For over a decade, React's virtual DOM was the mental model everyone copied. In 2026, that's changed: SolidJS proved that signals with surgical DOM updates outperform React's diffing by a meaningful margin, and Svelte 5 adopted runes to bring similar fine-grained updates to its compiler model. React's response — the React Compiler (shipping with React 19) — is an automatic memoization pass that closes some of the gap without changing the programming model.

These three frameworks represent three distinct theories about where reactivity should live: in runtime primitives (SolidJS), in a compiler (Svelte), or in an optimizing compiler layered over hooks (React).

TL;DR

SolidJS has the most efficient reactivity model: signals are the finest possible granularity, updates are surgical, and there's no component re-rendering at all — only the specific DOM nodes that depend on a signal update. Svelte 5 achieves similar granularity with its rune system at the compiler level, with better ecosystem maturity and a gentler DX curve. React with the React Compiler closes the performance gap for typical applications — but still has a conceptual overhead (component re-renders, dependency arrays) that the signal-based frameworks eliminate. For performance-critical UIs, SolidJS is the leader. For practical day-to-day development with a team, Svelte 5 or React (with Compiler) are the pragmatic choices.

Key Takeaways

SolidJS signals: zero VDOM, no re-renders — only the exact DOM nodes that depend on a changed signal update
Svelte 5 runes ($state, $derived, $effect): compiler-enforced reactivity, equivalent granularity to SolidJS with a more ergonomic API
React Compiler (React 19): automatic memoization that eliminates manual useMemo/useCallback but still re-renders components (just fewer)
js-framework-benchmark: SolidJS and Svelte 5 consistently top the charts; React with Compiler meaningfully improves but doesn't fully close the gap
Bundle size: Svelte 5 compiles to smaller bundles (no runtime); SolidJS runtime is ~7KB; React runtime is ~45KB
Adoption: React ~190M downloads/week vs Svelte ~2.7M vs SolidJS ~1.5M — ecosystem matters
The gap shrinks at app scale: at typical CRUD app complexity, users can't feel the difference

At a Glance

	SolidJS	Svelte 5	React 19 (+ Compiler)
Reactivity model	Runtime signals	Compiler + runtime runes	Hooks + optional compiler
Re-renders	None (component = factory)	None (compiled to DOM ops)	Component re-renders (fewer with Compiler)
Granularity	Signal-level (finest)	Rune-level (equivalent)	Hook call level (coarser)
Bundle size (min+gz)	~7KB	~5KB (no runtime)	~45KB
npm downloads/week	~1.5M	~2.7M	~190M
GitHub stars	~35K	~86K	~230K
Meta-framework	SolidStart	SvelteKit	Next.js, Remix, Tanstack Start
JSX	✅ (compile-time transformed)	❌ (`.svelte` templates)	✅
TypeScript	✅	✅ (`.svelte` with `<script lang="ts">`)	✅
React Compiler	N/A	N/A	✅ (React 19)
SSR	✅ SolidStart	✅ SvelteKit	✅ Next.js

How Reactivity Works: The Core Differences

SolidJS: Runtime Signals

SolidJS components are factory functions — they run once to set up subscriptions, then never run again. Updates happen at the signal level, directly mutating DOM nodes that are subscribed to that signal.

import { createSignal, createEffect, createMemo } from 'solid-js'

// Component runs ONCE — not on every update
function Counter() {
  const [count, setCount] = createSignal(0) // signal: reactive primitive

  // createMemo: derived computation, updates only when count() changes
  const doubled = createMemo(() => count() * 2)

  // createEffect: runs when dependencies change
  createEffect(() => {
    console.log(`Count changed to ${count()}`)
  })

  // The JSX compiles to direct DOM operations, not VDOM
  return (
    <div>
      {/* Only this text node updates when count() changes — nothing else */}
      <p>Count: {count()}</p>
      <p>Doubled: {doubled()}</p>
      <button onClick={() => setCount(c => c + 1)}>Increment</button>
    </div>
  )
}

The critical difference: count is a function (count()) not a value. The getter creates a subscription — when this JSX expression is evaluated in a reactive context (during the initial render), SolidJS records "this DOM node reads count." When setCount() is called, only those specific DOM nodes update.

Svelte 5: Runes

Svelte 5 replaced its let/$: reactive syntax with explicit runes — compiler-recognized functions that signal reactivity intent:

<script lang="ts">
  // $state: reactive state declaration
  let count = $state(0)

  // $derived: computed value (auto-tracks dependencies)
  let doubled = $derived(count * 2)

  // $effect: side effects (auto-tracks, reruns when deps change)
  $effect(() => {
    console.log(`Count changed to ${count}`)
  })
</script>

<!-- Template compiles to direct DOM operations -->
<p>Count: {count}</p>
<p>Doubled: {doubled}</p>
<button onclick={() => count++}>Increment</button>

Unlike SolidJS, count is a regular value (not a function call). The Svelte compiler statically analyzes which assignments can cause updates and generates the imperative DOM code. The result is equivalent granularity to SolidJS signals, but with a more natural syntax — you write count++ not setCount(c => c + 1).

React 19 with the React Compiler

React's model is fundamentally component-centric: state changes trigger component re-renders, and the reconciler diffs the new virtual DOM against the previous one.

import { useState, useMemo, useEffect } from 'react'

// 'use client' or just a component — re-renders when count changes
function Counter() {
  const [count, setCount] = useState(0)

  // Without Compiler: must manually memoize
  const doubled = useMemo(() => count * 2, [count])

  useEffect(() => {
    console.log(`Count changed to ${count}`)
  }, [count])

  // ENTIRE component re-renders on every setCount()
  // React Compiler: automatically memoizes stable sub-trees
  return (
    <div>
      <p>Count: {count}</p>
      <p>Doubled: {doubled}</p>
      <button onClick={() => setCount(c => c + 1)}>Increment</button>
    </div>
  )
}

The React Compiler (shipping with React 19) performs a Babel transform pass that automatically adds memoization to stable expressions — eliminating the need for manual useMemo, useCallback, and React.memo. But it doesn't eliminate component re-renders; it just ensures that stable sub-trees are memoized and skip reconciliation.

Performance: When the Difference Is Real

js-framework-benchmark Results (2025-2026)

The benchmark measures DOM operations: create 1K rows, select/swap/remove rows, create 10K rows.

Framework	Geometric Mean Score	vs React baseline
Vanilla JS	1.00	baseline
SolidJS	~1.08	2x faster than React
Svelte 5	~1.10	1.9x faster than React
Vue 3 (signals)	~1.30	1.6x faster than React
React 19 (no compiler)	~2.05	baseline
React 19 (with Compiler)	~1.70	~1.2x faster than base React

Lower is better (multiplier of vanilla JS baseline). React with Compiler is a real improvement but SolidJS and Svelte 5 remain ~50-60% faster on heavy DOM manipulation workloads.

When the Benchmark Numbers Don't Matter

The benchmark measures extreme DOM-heavy scenarios. In most production apps:

Component tree: ~50-200 components
Update frequency: ~10-100ms between state changes
User-perceptible: differences < 16ms (one frame) are invisible

At this scale, React + Compiler, SolidJS, and Svelte 5 all feel instant.
The performance difference matters for:
- Data grids with 10,000+ rows
- Real-time dashboards updating > 30fps
- Complex animations with many tracked values
- Mobile devices with limited JS thread budget

Reactivity Patterns Compared

Derived State

// SolidJS
const total = createMemo(() => items().reduce((sum, item) => sum + item.price, 0))
// Re-computes only when items() changes

// Svelte 5
let total = $derived(items.reduce((sum, item) => sum + item.price, 0))
// Same — static analysis determines dependency

// React (with Compiler — no useMemo needed)
const total = items.reduce((sum, item) => sum + item.price, 0)
// Compiler automatically memoizes this if items is stable

Effects and Cleanup

// SolidJS
createEffect(on(userId, (id) => {
  const subscription = subscribeToUser(id)
  onCleanup(() => subscription.unsubscribe())
}))

// Svelte 5
$effect(() => {
  const subscription = subscribeToUser(userId)
  return () => subscription.unsubscribe() // cleanup function
})

// React
useEffect(() => {
  const subscription = subscribeToUser(userId)
  return () => subscription.unsubscribe()
}, [userId])

Stores / Global State

// SolidJS: createStore for nested object reactivity
import { createStore, produce } from 'solid-js/store'

const [store, setStore] = createStore({ user: { name: 'Alice', count: 0 } })
setStore('user', 'count', c => c + 1)  // Only user.count DOM nodes update

// Svelte 5: $state works at any scope, including module scope
// store.svelte.ts:
export const userStore = $state({ name: 'Alice', count: 0 })
// Import and use directly — reactive everywhere

// React: Zustand, Jotai, or Context (not built-in fine-grained stores)

Bundle Size: The Compiler Advantage

Svelte's compile-to-vanilla-JS approach means apps ship with zero framework runtime:

React 19 runtime:        ~45KB (min+gz)
SolidJS runtime:          ~7KB (min+gz)
Svelte 5 runtime:         ~5KB (min+gz) — mostly for SSR hydration
Svelte 5 (CSR-only):    ~2-3KB (min+gz)

For large apps, the runtime cost is amortized over component code — but for small apps and first-party scripts, Svelte's approach is dramatically more efficient.

The Signals Convergence

Fine-grained reactivity is winning. In 2026, it's not just SolidJS and Svelte — Vue 3 ships signals via its Composition API, Angular 20 introduced native signals as a first-class primitive, and even React's Compiler is a pragmatic concession that the old "re-render everything" model needs help. The ecosystem has converged on the idea that tracking precise reactive dependencies is the right model.

This convergence matters for your framework choice: if you're evaluating SolidJS or Svelte 5 today, you're choosing a framework where the reactivity model is the primary design — not a feature bolted on. React is adapting. The others were built around it.

When to Choose Each

Choose SolidJS When:

You need the absolute best DOM performance (real-time dashboards, games, data grids)
Your team is comfortable with signals as the primary primitive
You're building a new project and don't need React's ecosystem
JSX is preferred over template syntax
You want the most "pure" reactive system — no compiler magic, just runtime logic

Choose Svelte 5 When:

You want fine-grained reactivity with ergonomic syntax (write count++ not setCount(c => c + 1))
Smallest possible bundle size matters
Your team doesn't have a React background to migrate
You're building content-heavy sites where SvelteKit shines
You want a self-contained framework with routing (SvelteKit), stores, and transitions built in

Choose React (with Compiler) When:

Your team already knows React — migration cost is real
You need the largest ecosystem: component libraries, hiring pool, tutorials
You're building on Next.js (App Router, PPR, Server Components)
Enterprise environment where ecosystem stability matters more than peak performance
You need React Server Components for zero-bundle server-rendered components

Compare SolidJS, Svelte, and React download trends on PkgPulse.