Why Vue 3.6’s Experimental Vapor Mode Could Ditch VDOM for Faster Rendering

Introduction

At Vue Conf on 2025/07/25 the team announced that Vue 3.6 will support an experimental Vapor Mode that gradually removes the virtual DOM (VDOM). The goal is to replace VDOM’s runtime overhead with compile‑time generated rendering APIs, though this introduces compilation pressure and potential bundle‑size growth.

Soul Three Questions

1. Why get rid of the VDOM?

Because it’s faster – the VDOM has inherent performance bottlenecks.

Historically VDOM was introduced to improve speed: after a diff, it reduces unnecessary DOM operations, even though it adds JavaScript computation. Direct native DOM manipulation can be even faster if it avoids extra work, but VDOM generally offers better performance for typical apps.

Why was VDOM fast? Native code is the fastest, but VDOM adds a diff step that cuts down on redundant DOM calls, which are the biggest performance cost.

Why will removing VDOM be faster now? Removing VDOM doesn’t force you to write raw native code; the new Vapor Mode provides a more efficient path, explained below.

In previous Vue versions, the smallest update unit was the component: any reactive data change triggered a full component re‑render, producing VDOM → diff → real DOM update. This approach has two main bottlenecks:

Excessive recomputation All components recompute their VDOM even if only a few reactive nodes changed, leading to unnecessary calculations.

Redundant DOM updates/generation After diffing, some updates are still superfluous, especially in complex scenarios.

Even with many optimizations, these issues persist, so moving toward a VDOM‑free architecture can approach native performance.

2. Why is Vapor Mode faster than VDOM?

Vapor operates at the element level, similar to Svelte: when reactive data changes, only the directly affected elements are updated, eliminating the component‑wide VDOM diff.

3. How does Vue handle cross‑platform rendering without a VDOM layer?

VDOM offered two benefits: fewer DOM updates and an abstraction layer for cross‑platform UI description. Traditional cross‑platform frameworks (e.g., uniapp) replace Vue’s renderer with platform‑specific APIs while keeping the same template syntax.

Without VDOM, the renderer works on a lower‑level abstract rendering code generated at compile time. This abstract code is atomic, and the renderer’s job becomes simply implementing these rendering functions.

<span>const text = createText('dkh');</span></code><code><span>// Implementation lives in the renderer</span></code><code><span>function createText(txt = '') {</span></code><code><span>  // ...</span></code><code><span>}</span>

The abstract layer decouples VDOM‑to‑UI logic, so even after removing VDOM, existing cross‑platform frameworks need minimal changes—only the VDOM‑to‑abstract conversion is altered.

Current Issues with Vapor Mode

Although Vapor promises to outperform VDOM, it is still experimental and has drawbacks:

All VDOM‑related runtime calculations are shifted to compile time, which can increase compilation time and complexity.

If a project contains many components, the generated code may duplicate heavily, inflating bundle size.

The second issue is the most significant. Svelte faces similar challenges, but so far Vapor has not shown severe problems. Since Vapor currently coexists with VDOM, future Vue 4 may drop VDOM entirely if market adoption is strong.

Thanks for reading; feel free to share your thoughts in the comments.