butter smooth performance in xamarin forms listview

FastCell.cs

using System;

using Xamarin.Forms;

namespace TwinEvents.Core.Media.View
{
	public class FastCell : ViewCell
	{
	}
}

FastCellRenderer.cs

using System;
using Xamarin.Forms.Platform.iOS;
using Foundation;
using UIKit;
using Xamarin.Forms;
using TwinEvents.Ios.Media;
using TwinEvents.Core.Media.View;

[assembly: ExportRenderer (typeof(FastCell), typeof(FastCellRenderer))]
namespace TwinEvents.Ios.Media
{
	internal class NativeCell : UITableViewCell
	{
		UIView _view;

		public ViewCell XamarinView {
			get;
			set;
		}

		bool _isViewLaidOut;

		public NativeCell (NSString cellId, ViewCell view) : base (UITableViewCellStyle.Default, cellId)
		{
			XamarinView = view;

			var renderer = RendererFactory.GetRenderer (view.View);
			_view = renderer.NativeView;
			ContentView.AddSubview (_view);
		}

		public override void LayoutSubviews ()
		{
			base.LayoutSubviews ();
			//TODO update sizes of the xamarin view
			if (!_isViewLaidOut) {
				var layout = XamarinView.View as AbsoluteLayout;
				layout.Layout (Frame.ToRectangle ());
				layout.ForceLayout ();
				_isViewLaidOut = true;
			}

			_view.Frame = ContentView.Bounds;
		}
	}

	public class FastCellRenderer : ViewCellRenderer
	{
		NSString cellId = new NSString ("Cell");

		public override UITableViewCell GetCell (Cell item, UITableViewCell reusableCell, UITableView tv)
		{
			var nativeCell = tv.DequeueReusableCell (cellId) as NativeCell;
			var viewCell = item as ViewCell;

			if (nativeCell == null) {
				nativeCell = new NativeCell (cellId, viewCell);
			} else {
				nativeCell.XamarinView.BindingContext = item.BindingContext;
			}

			return nativeCell;
		}
	}
}

FastImage.cs

using System;

using Xamarin.Forms;
using System.Diagnostics;

namespace TwinEvents.Core.Media.View
{
	public interface IFastImageProvider
	{
		void SetImageUrl (string imageUrl);
	}

	public class FastImage : Image
	{

		public static readonly BindableProperty ImageUrlProperty = BindableProperty.Create<FastImage, string> (w => w.ImageUrl, null);

		/// <summary>
		/// sets the image URL.
		/// </summary>
		/// <value>The image URL.</value>
		public string ImageUrl {
			get { return (string)GetValue (ImageUrlProperty); }
			set { 
				SetValue (ImageUrlProperty, value);
			}
		}
	}
}

FastImageRenderer

using System;
using Xamarin.Forms.Platform.iOS;
using XLabs.Platform.Device;
using UIKit;
using SDWebImage;
using Foundation;
using TwinEvents.Core.Media.View;
using Xamarin.Forms;
using TwinEvents.Ios.Media;

[assembly: ExportRenderer (typeof(FastImage), typeof(FastImageRenderer))]
namespace TwinEvents.Ios.Media
{
	public class FastImageRenderer : ImageRenderer, IFastImageProvider
	{
		public FastImageRenderer ()
		{
		}

		protected override void OnElementChanged (ElementChangedEventArgs<Image> e)
		{
			base.OnElementChanged (e);
//			if (e.OldElement != null) {
//				((FastImage)e.OldElement).ImageProvider = null;
//			}
			if (e.NewElement != null) {
				var fastImage = e.NewElement as FastImage;
				SetImageUrl (fastImage.ImageUrl);
			}
		}

		protected override void OnElementPropertyChanged (object sender, System.ComponentModel.PropertyChangedEventArgs e)
		{
			base.OnElementPropertyChanged (sender, e);
			if (e.PropertyName == "ImageUrl") {
				var fastImage = Element as FastImage;
				SetImageUrl (fastImage.ImageUrl);
			}
		}

		#region FastImageProvider implementation

		public void SetImageUrl (string imageUrl)
		{
			if (Control == null) {
				return;
			}
			if (imageUrl != null) {
				Control.SetImage (
					url: new NSUrl (imageUrl), 
					placeholder: UIImage.FromBundle ("placeholder.png")
				);
			} else {
				Control.Image = UIImage.FromBundle ("placeholder.png");
			}
		}

		#endregion
	}
}

MediaCellXaml.xaml

<?xml version="1.0" encoding="UTF-8"?>
<!-- example cell -->
<local:FastCell xmlns="http://xamarin.com/schemas/2014/forms" 
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
x:Class="TwinEvents.Core.Media.View.MediaCellXaml"
xmlns:local="clr-namespace:TwinEvents.Core.Media.View;assembly=TwinEvents"
>
	<AbsoluteLayout BackgroundColor="Black">
		<local:FastImage x:Name="ImageView" AbsoluteLayout.LayoutFlags="None" AbsoluteLayout.LayoutBounds="0,0,320,260"/>
		<local:FastImage x:Name="UserThumbnailView" AbsoluteLayout.LayoutFlags="None" AbsoluteLayout.LayoutBounds="5,240,40,40"/>
		<Label x:Name="NameLabel" Text="some text" TextColor="White"  AbsoluteLayout.LayoutFlags="None" AbsoluteLayout.LayoutBounds="50,250,100,20"/>
		<Label x:Name="DescriptionLabel" Text="some text" TextColor="White" AbsoluteLayout.LayoutFlags="None" AbsoluteLayout.LayoutBounds="50,270,100,40"/>
	</AbsoluteLayout>
</local:FastCell>

MediaCellXaml.xaml.cs

using System;
using System.Collections.Generic;
using Xamarin.Forms;
using TwinEvents.Core.Media.Model;

//Example cell code behind
namespace TwinEvents.Core.Media.View
{
	public partial class MediaCellXaml : FastCell
	{
		public MediaCellXaml ()
		{
			InitializeComponent ();
		}

		protected override void OnBindingContextChanged ()
		{
			base.OnBindingContextChanged ();
			var mediaItem = BindingContext as IMediaItem;
			if (mediaItem != null) {
//				UserThumbnailView.Source = mediaItem.UserThumbnailImageSource;
//				ImageView.Source = mediaItem.ImageSource;
				UserThumbnailView.ImageUrl = mediaItem.UserThumbnailPath != null ? mediaItem.UserThumbnailPath.AbsoluteUri : null;
				ImageView.ImageUrl = mediaItem.UserThumbnailPath != null ? mediaItem.ImagePath.AbsoluteUri : null;
//				NameLabel.Text = mediaItem.Name;
			}
		}
	}
}

what's that .... ??? I saw on the xamarin blog page this code

<ListView.ItemTemplate>


...


</ListView.ItemTemplate>