用el-select 如果option数量多 el-select就会很卡。

directives:{
    'el-select-loadmore':(el,binding)=>{
        const Dom=el.querySelector('.el-select-dropdown .el-select-dropdown__wrap')
        if(Dom){
            Dom.addEventListener('scroll',function(){
                const condition = this.scrollHeight - this.scrollTop <= this.clientHeight;
                 if(condition) binding.value()
            })
        }
    }
},
data(){
    return {
        val:'',
        pageNum:1,
        pageSize:100,
        options:[],
        allOption:[]
    }
}
methods:{
    loadMore(){
        return ()=>{
          this.pageNum+=1
        let arr = this.allOption.slice((this.pageNum-1)*this.pageNum,this.pageNum*this.pageSize)
          this.options.push(...arr)
        }
    }
}

<el-select v-el-select-loadmore="loadMore" v-mode="val">
    <option v-for="item in options"></option>
</el-select>