uniapp nuve 模式做的聊天App，再聊天页面，加载过多的内容后，低端手机会

<template>  
    <div @longpress="long">  
        <!-- 时间显示 -->  
        <view v-if="showTime"   
        class="flex align-center justify-center pb-4 pt-2">  
            <text class="font-sm text-light-muted">{{showTime}}</text>  
        </view>  
        <!-- 撤回消息 -->  
        <view v-if="item.isremove == 1" ref="isremove"  
        class="flex align-center justify-center pb-4 pt-1">  
            <text class="font-sm text-light-muted">{{ isself ? '你' : '对方' }}撤回了一条信息</text>  
        </view>  
        <!-- 系统消息 -->  
        <view v-if="item.type === 'system'" ref="isremove"  
        class="flex align-center justify-center pb-4 pt-1">  
            <text class="font-sm text-light-muted">{{item.data}}</text>  
        </view>  
        <!-- 进群消息 -->  
        <view v-if="item.type === 'join'"   
        class="flex align-center justify-center pb-4 pt-1">  
            <text class="font-sm text-light-muted">{{item.data}}</text>  
        </view>  
        <!-- 进群消息 -->  
        <view v-if="item.type === 'invite'"   
        class="flex align-center justify-center pb-4 pt-1">  
            <text class="font-sm text-light-muted">{{item.data}}</text>  
            <text class="font-sm text-light-muted text-info" @click="inviteConfirm">{{item.isconfirm ? "已确认":"确认"}}</text>  
        </view>  
        <!-- 气泡 -->  
        <view v-if="item.type !== 'system' && item.type !== 'join'  && item.type !== 'invite' && item.isremove == 0" class="flex align-start position-relative mb-3"  
        :class="!isself ? 'justify-start' : 'justify-end'">  

            <!-- 好友 -->  
            <template v-if="!isself">  
                <free-avater size="70" :src="item.from_avatar" @click="openUser"></free-avater>  
                <text v-if="hasLabelClass" class="iconfont text-white font-md position-absolute chat-left-icon" :style="shownickname ? 'top:45rpx;':'top:20rpx;'">&#xe609;</text>  
            </template>  

            <view class="flex flex-column">  
                <!-- 昵称 -->  
                <view v-if="shownickname" class="flex" :class="nicknameClass" style="max-width:500rpx;background-color: rgba(0,0,0,0);" :style="labelStyle">  
                    <text class="font-sm text-muted">{{item.from_name}}</text>  
                </view>  

                <div class="p-2 rounded" :class="labelClass" style="max-width:500rpx;" :style="labelStyle">  
                    <!-- 文字 -->  
                    <text v-if="item.type === 'text'" class="font-md">{{item.data}}</text>  
                    <!-- 表情包 | 图片-->  
                    <free-image @longpress="stop" v-else-if="item.type === 'emoticon' || item.type === 'image'" :src="item.data" @click="preview(item.data)" imageClass="rounded" :maxWidth="500" :maxHeight="350"></free-image>  

                    <!-- 音频 -->  
                    <view v-else-if="item.type === 'audio'"   
                    class="flex align-center"  
                    @tap="openAudio" @longpress="stop">  
                        <image v-if="isself" :src=" !audioPlaying ? '/static/audio/audio3.png' : '/static/audio/play.gif'"   
                        style="width: 50rpx;height: 50rpx;"   
                        class="mx-1"></image>  
                        <text class="font">{{item.options.time + '"'}}</text>  
                        <image v-if="!isself" :src=" !audioPlaying ? '/static/audio/audio3.png' : '/static/audio/play.gif'"  
                        style="width: 50rpx;height: 50rpx;"   
                        class="mx-1"></image>  
                    </view>  

                    <!-- 视频 -->  
                    <view v-else-if="item.type === 'video'"  
                    class="position-relative rounded"  
                    @tap="openVideo" @longpress="stop">  
                        <free-image :src="item.options.poster" imageClass="rounded" :maxWidth="300" :maxHeight="350" @load="loadPoster"></free-image>  
                        <text class="iconfont text-white position-absolute" style="font-size: 80rpx;width: 80rpx;height: 80rpx;" :style="posterIconStyle">&#xe737;</text>  
                    </view>  

                    <!-- 名片 -->  
                    <view v-else-if="item.type === 'card'" class="bg-white" style="width: 400rpx;" hover-class="bg-light" @tap="openUserBase" @longpress="stop">  
                        <view class="p-3 flex align-center border-bottom border-light-secondary">  
                            <free-avater size="70"   
                            :src="item.options.avatar"  
                            clickType="navigate"></free-avater>  
                            <text class="font ml-2">{{item.data}}</text>  
                        </view>  
                        <view class="flex align-center p-2">  
                            <text class="font-small text-muted">个人名片</text>  
                        </view>  
                    </view>  
                </div>  

            </view>  
            <!-- 本人 -->  
            <template v-if="isself">  
                <text v-if="hasLabelClass" class="iconfont text-chat-item font-md position-absolute chat-right-icon" :style="shownickname ? 'top:45rpx;':'top:20rpx;'">&#xe640;</text>  
                <free-avater size="70" :src="item.from_avatar"  
                @click="openUser"></free-avater>  
            </template>  

        </view>  

        <view v-if="item.sendStatus && item.sendStatus !== 'success'" class="flex align-center justify-end px-4">  
            <text class="font-sm" :class="item.sendStatus === 'fail' ? 'text-danger' : 'text-muted'">{{item.sendStatus === 'fail' ? '发送失败' : '发送中...'}}</text>  
        </view>  

    </div>  
</template>  

shownickname="currentChatItem.shownickname"

</free-chat-item>
</cell>

</list>  

比如在红米9a 这种老年机里面就非常卡，页面几乎不会动，但是同样的微信很流畅，为什么呢