[Bug Report] Cascader组件设置多选，全选某菜单后清除全部出现明显卡顿

### Element UI version
2.15.10

### OS/Browsers version
MacOS

### Vue version
2.7.13

### Reproduction Link
https://codepen.io/nieyuyao/pen/NWzKbqE

### Steps to reproduce
1. 勾选指南菜单，进行全选
2. 点击清除全部
3. 出现明显的卡顿

### What is Expected?
快速清除全部菜单

### What is actually happening?
点击清除全部后，出现明显的卡顿