Android recyclerview poor performance after API 27 to 29 Migration

Question

Migrated app to support latest API 29. All has gone very well, app functions correctly, except for one perplexing issue; A recyclerview is populated using a SQLite query, which may retrieve 500+ records, and displays the result in a detail activity that looks like this.

This has always worked fine on API 27 with the detail activity opened & populated almost instantly, while the sql call, activity code and layout hasn't changed in 5 years. However, on the API 29 version, using the same code, the app takes 3+ seconds to display the same data

After much testing and reading Slow Rendering, I think I've nailed it down to androidx.recyclerview:recyclerview:1.0.0 in API 29 taking much longer to build the output for the activity UI, possibly due to my poor coding and/or layout structure.

This is my R.layout.msgh_detail populated by the .java

<?xml version="1.0" encoding="utf-8"?>

<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent">

<com.google.android.material.appbar.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:layout_collapseMode="pin" />

</com.google.android.material.appbar.AppBarLayout>

<androidx.core.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="75dp"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_vertical"
        android:orientation="vertical">

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/msgh_detail_list" />

    </LinearLayout>

</androidx.core.widget.NestedScrollView>

<androidx.cardview.widget.CardView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/replyCard"
    android:layout_marginBottom="2dp"
    android:layout_marginLeft="@dimen/card_margin"
    android:layout_marginRight="@dimen/card_margin"
    android:layout_gravity="bottom"
    android:layout_alignParentBottom="true"
    android:touchscreenBlocksFocus="false">

    <LinearLayout
        style="@style/Widget.CardContent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textMultiLine|textCapSentences"
            android:maxLength="250"
            android:ems="10"
            android:imeOptions="actionDone"
            android:id="@+id/msg_reply"
            android:hint="@string/msg_reply_hint" />
    </LinearLayout>

</androidx.cardview.widget.CardView>

<com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_anchor="@id/replyCard"
        app:layout_anchorGravity="top|right|end"
        android:layout_margin="8dp"
        android:src="@drawable/ic_send_white_24dp" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

Here is the include R.layout.msgh_detail_list_item via .java ViewHolder

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:paddingTop="4dp"
android:paddingBottom="4dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:gravity="center_vertical"
android:orientation="vertical">
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="24dp"
    android:orientation="horizontal">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="8dp"
        android:layout_weight="0.97"
        android:id="@+id/DayMMdd"
        android:ellipsize="end"
        android:maxLines="1"
        android:hint="@string/day_mth_dte" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/arrivaltime"
        android:layout_marginLeft="8dp"
        android:hint="@string/Hour_min" />

    <ImageView
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:id="@+id/avatar"
        android:src="@drawable/status_1"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:longClickable="false" />

</LinearLayout>


<androidx.cardview.widget.CardView
    android:id="@+id/detail_cardview"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:cardBackgroundColor="#ccecf9">

    <LinearLayout
        style="@style/Widget.CardContent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/text2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textAppearance="?attr/textAppearanceListItem"
            android:autoLink="web"
            android:textColorLink="#009933"
            android:layout_weight="0.97"
            android:text="@string/test_msg" />

    </LinearLayout>

</androidx.cardview.widget.CardView>

</LinearLayout>

Clearly, there's quite a lot going on here and, frankly, I'm amazed it works so well, or at least it did until androidx and API version 29 came along..!

QUESTION: The issue is that the app gets exceedingly slow on a 300+ recordset and I'm a bit stumped on how to fix it...

LATER FIXED!: Revised R.layout.msgh_detail subsequent to tip by @martin-zeitler that now seems to work properly and load data pretty much instantly.

Removed entire androidx.core.widget.NestedScrollView block and replaced with androidx.recyclerview.widget.RecyclerView from the include layout (now discarded).

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent">

<com.google.android.material.appbar.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:layout_collapseMode="pin" />

</com.google.android.material.appbar.AppBarLayout>

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/detail_recyclerview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginBottom="70dp"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

<androidx.cardview.widget.CardView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/replyCard"
    android:layout_marginBottom="2dp"
    android:layout_marginLeft="@dimen/card_margin"
    android:layout_marginRight="@dimen/card_margin"
    android:layout_gravity="bottom"
    android:layout_alignParentBottom="true"
    android:touchscreenBlocksFocus="false">

    <LinearLayout
        style="@style/Widget.CardContent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textMultiLine|textCapSentences"
            android:maxLength="250"
            android:ems="10"
            android:imeOptions="actionDone"
            android:id="@+id/msg_reply"
            android:hint="@string/msg_reply_hint" />
    </LinearLayout>

</androidx.cardview.widget.CardView>

<com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_anchor="@id/replyCard"
        app:layout_anchorGravity="top|right|end"
        android:layout_margin="8dp"
        android:src="@drawable/ic_send_white_24dp" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

Answer 1

Also noticed that once, that it became quite sluggish ...

The problem is likely that NestedScrollView > LinearLayout > RecyclerView.

Also that include is pretty useless, with one single node contained.... you have to nest it like this:

<androidx.core.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:isScrollContainer="true"
    android:longClickable="false"
    android:measureAllChildren="true"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        tools:listitem="@layout/cardview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:color="?android:colorControlHighlight"
        android:fastScrollEnabled="true"
        android:gravity="start"
        android:scrollbarStyle="insideInset"
        android:scrollbars="vertical"
        android:splitMotionEvents="false"
        android:verticalScrollbarPosition="right"/>

</androidx.core.widget.NestedScrollView>