TL;DR

Vue 3.6 introduces Vapor Mode, a high-performance compilation mode that reduces bundle size and matches the speed of Solid and Svelte 5.

New

• Vapor Mode: An opt-in compilation strategy for SFCs that bypasses VNodes (virtual DOM nodes) to improve performance.
• Reactivity Overhaul: A major refactor of @vue/reactivity using alien-signals (a high-performance signal implementation) to reduce memory usage and increase speed.

Fixes Worth Knowing

• Resolved several hydration and slot-related bugs specifically affecting Vapor Mode and SSR (Server-Side Rendering).
• Fixed v-if and v-show behavior on transition roots within Vapor components.

Before You Upgrade

• To use Vapor Mode, add the vapor attribute to your script tag: <script setup vapor>.
• Note that Vapor Mode does not support the Options API or features relying on the component public instance proxy.

TL;DR

This release focuses on stability improvements across the core framework, specifically targeting hydration and server-side rendering (SSR) reliability.

Fixes Worth Knowing

• SSR & Hydration: Resolved issues with dynamic prop patching, lazy hydration for detached roots, and comment escaping in server-rendered content.
• Runtime: Fixed a bug where <select> elements did not correctly respect the model type.
• Reactivity: Improved handling of effect removal during scope stops.
• Types: Relaxed constraints on the component $el type to allow for non-Element values.