添加一个imageview后滑动有点卡顿

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.xudongting.moocshowapp.MainActivity">

    <SearchView
        android:id="@+id/searchView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:iconifiedByDefault="false"
        android:queryHint="亲，想搜索啥子呢？" />

    <ListView
        android:layout_below="@id/searchView"
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

    </ListView>
    <ImageView
        android:layout_marginBottom="20dp"
        android:layout_marginRight="20dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:src="@drawable/timg"
        android:layout_width="60dp"
        android:layout_height="60dp" />


</RelativeLayout>

就是不添加这个imageview之前滑动很流畅，添加之后就有点卡顿了，这个是模范作业里面那个悬浮的红色邮件，这样添加有没有问题呢？