The best way to deal with user interface performance issues in Windows Phone 8.1

Question

I seem to have a sluggish user interface when trying to scroll through any large text blocks ...
What is the best way to do this in WP 8.1?

Here is an example that I did to illustrate this problem, note when the application starts, the frame rate drops terribly.
I already looked BackgroundWorkerand it doesn't seem to exist in WP 8.1.

MainPage.xaml

<Page
    x:Class="HTTPRequest.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:HTTPRequest"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <Grid>
        <ScrollViewer x:Name="scroll" Margin="10,13,0,10" Width="380" MaxZoomFactor="4" VerticalScrollMode="Enabled" HorizontalScrollMode="Disabled" IsTapEnabled="False">
            <TextBlock x:Name="RSSData" TextWrapping="Wrap" Text="Loading..." FontSize="22" VerticalAlignment="Top"/>

        </ScrollViewer>
        <ProgressBar x:Name="prog" Height="16" Margin="101,310,101,0" VerticalAlignment="Top" IsIndeterminate="True"/>

    </Grid>
</Page>

MainPage.xaml.cs

using System;
using System.ComponentModel;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Text;
using System.Threading.Tasks;
using Windows.Data.Xml.Dom;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=391641

namespace HTTPRequest
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();

            this.NavigationCacheMode = NavigationCacheMode.Required;

            Main();
        }

        private async void Main()
        {
            string results = await DownloadXMLDocument();
            prog.Visibility = Visibility.Collapsed;
            RSSData.Text = results;
        }

        public async Task<string> DownloadXMLDocument()
        {
              string URLString = "http://www.packtpub.com/rss.xml";
              Uri uri = new Uri(URLString);
              XmlDocument xmlDocument = await XmlDocument.LoadFromUriAsync(uri);
              return xmlDocument.GetXml();
        }



        /// <summary>
        /// Invoked when this page is about to be displayed in a Frame.
        /// </summary>
        /// <param name="e">Event data that describes how this page was reached.
        /// This parameter is typically used to configure the page.</param>
        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            // TODO: Prepare page for display here.

            // TODO: If your application contains multiple pages, ensure that you are
            // handling the hardware Back button by registering for the
            // Windows.Phone.UI.Input.HardwareButtons.BackPressed event.
            // If you are using the NavigationHelper provided by some templates,
            // this event is handled for you.
        }
    }
}

Answer 1

TextBox. RichTextBox , . , .

!