Tree Checking is very slow and causes a large re-render when you have a lot of nodes expanded

[iamBevan]

• I have searched the issues of this repository and believe that this is not a duplicate.

Version

3.2.16

Environment

Vue 3.2.47

Reproduction link

Steps to reproduce

Load ~1000 items into tree data and expand all the items, check the root level node

What is expected?

The tree should be able to efficiently manage checking nodes when they have many expanded child items

What is actually happening?

The tree takes 2-4 seconds to render the checkbox ticks and locks up the system

[hisuwh]

It would seem the virtual scroll implementation in the Vue 3 version is not the same as the React version.

• In the React implementation of virtual scroll on the tree component it only renders nodes in the dom that are visible and removes those at the top as they become invisible
• In the Vue 3 version it only seems to add nodes as you scroll, meaning performance slowly degrades as you get further down (scrolling is also horrifically slow with a large tree as can be seen in the sandbox above).

[tangjinzhou]

https://codesandbox.io/s/hidden-platform-d181b7?file=/src/App.vue

please use number type :height="500"

[github-actions]

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