Windows 8.1 enables you to compile XAML applications into assemblies using the XAML Binary Format (XBF). Moreover, load and render time of apps has been significantly improved since all the required keyed resources are not completely loaded at startup but rather follow a deferred loading scheme.
XAML developers will be able to see panning improvements in applications under Windows 8.1 which will be visible when navigating through large lists of items. Moreover, gray box placeholders will be displayed till all the items from the database are rendered. Windows 8.1 also includes improvements in the design-time performance of the XAML editor in Visual Studio 2013.
The XAML editor included with Visual Studio 2013 includes IntelliSense for keyed resources in addition to full data binding. The IntelliSense has a built-in ability to display correct element name if you don't even know the correct naming structure in addition to F12 support. The editor also provides support for CamelCase matching which displays the correct element name if you provide the capitalized portion.
According to official sources, Visual Studio 2013 XAML editor will include expansion and surroundwith snippets. Currently, Viusal Studio 2013 Preview does not include any snippets but you can create custom snippet if you follow the tutorial provided by Tim Heuer.
It is also possible to drag an instance of a XAML control directly into the document outline, which enables you to place your control exactly where you want it in the visual tree without having to navigate through XAML markup. Visual Studio 2013 has an ability to automatically detect existing comments within the selection and wrap them inside the XAML code editor. Moreover, closing tags are removed if the engine detects a end tag for an element.
Visual Studio 2013 includes theming enhancements with which you can set the theme at any time till compilation stage. As of now, you don't have this ability and have to select a theme during the creation of the project. It also includes several new controls such as Search, menu Flyout, CommandBar, AppBarButton, AppBarToggleButton and AppBarSeparator, which implement Windows Store application guidelines including the ability to assign the iconography for AppBarButtons using the properties panel.
XAML developers in Windows 8.1 can make use of the new Hub control that enables you to create HubSections to split up your content in addition to Hyperlink control. Moreover, ComboBox, Slider, DatePicker, TimePicker, Textbox, PasswordBox and RichEditBox control includes Header template property including the ability to add Placeholder text and watermarks.
Windows 8.1 provides an ability to render the XAML visual tree as an image using RenderTargetBitmap in the Windows.Xaml.Media.Imaging namespace.It also includes updated project, hub App and coded UI test project templates including the ability to record tests for Windows Store applications and play them when required.