页面上有个fixed悬浮按钮，希望可以在页面上任意拖动位置，但是现在的问题是写出来的拖动效果特别不流畅（反应延迟），请问有什么好的办法解决？

<view class='helpbox' style="bottom:{{bottom}}px;right:{{right}}px;" catchtouchmove='setTouchMove'>

<image class='helpimg' src='/images/help.png'></image>

</view>

js代码：

setTouchMove:function(e){

    var that = this;

    var width = 35 * rpx;

    var screenWidth = wx.getSystemInfoSync().windowWidth;

    var screenHeight = wx.getSystemInfoSync().windowHeight;

    var clientX = e.touches[0].clientX;

    var clientY = e.touches[0].clientY;

    //此处clientY与clientX为拖动悬浮窗超过设定的大小会返回默认显示位置

    if (clientX < (screenWidth - width) && clientY < (screenHeight - width) && clientX > width && clientY > width) {

        that.setData({

            right: screenWidth - clientX - width,

            bottom: screenHeight - clientY - width

        })

    } else {

        return;

        // that.setData({

        //   right: 0, //默认显示位置 left距离

        //   bottom: 0  //默认显示位置 top距离

        // })

    }

}