Vue 3.6 has officially entered the release candidate phase with the launch of v3.6.0-rc.1. This milestone marks the completion of the intended feature set for Vapor Mode, an experimental compilation strategy that optimizes runtime performance. Alongside this, the team has performed a major refactor of @vue/reactivity using the alien-signals library, resulting in substantial gains in reactivity system performance and memory usage.
Key Changes in v3.6.0-rc.1
- Vapor Mode feature set completed – The new compilation mode is now feature-complete and ready for broader testing. For details, see the dedicated "About Vapor Mode" section in the release notes.
- Reactivity system rewrite –
@vue/reactivitynow leverages alien-signals to improve tracking efficiency and reduce memory footprint, leading to faster reactive updates. - Bug fixes in hydration and Vapor runtime – Several hydration issues were resolved, including:
- Avoiding resolution of inherited fallback in forwarded slots (
4c215b5) - Removing adopted SSR DOM for unresolved async setup (
3859af4)
- Avoiding resolution of inherited fallback in forwarded slots (
- Vapor runtime patches – Fixed issues with slot content anchors during hydration, dynamic component hydration, and VNode slot content patching. Notable fixes include:
- Preservation of
v-showtransitions on VDOM children (fe882c9, closes #15073) - Cleanup of detached slot branches (
b41009d) - Safer slot dry runs during VDOM interop (
340630e)
- Preservation of
- Memory and stability improvements – Multiple fixes ensure slot anchors are preserved during mismatch recovery and that pending slot anchors are maintained correctly.
Why This Matters
This release brings Vue closer to a production-ready Vapor Mode, which promises drastically reduced overhead by compiling components down to imperative DOM manipulation. The reactivity rewrite based on alien-signals also means applications will see faster reactivity and lower memory usage, especially in large or complex state graphs. Developers are encouraged to test the RC in their projects and provide feedback before the final 3.6 release.
Source: https://github.com/vuejs/core/releases/tag/v3.6.0-rc.1