Here is a simple case: you use a Slider control to adjust the fontsize of a TextBlock.

XAML:

        <StackPanel>
            <TextBlock x:Name="ContentText" Text="Here is the simple text"/>
            <Slider x:Name="TextSizeSlider" Value="5" ValueChanged="TextSizeSlider_ValueChanged" Minimum="1"/>
        </StackPanel>

Code behind:

        private void TextSizeSlider_ValueChanged(object sender, RangeBaseValueChangedEventArgs e)
        {
            ContentText.FontSize = e.NewValue;
        }

Of course, change the FontSize of TextBlock is a low-cost operation which you will not even think about optimizing. However, there are some cases that you would perform a high-cost operation like aplying blurring effect to an Image, sending a HTTP request and so on. And in those cases frequent high-cost operations can result in slowing down the performance of your app or cause some unexpected issues.

So you may want to do some tricks to handle this issue: 500ms after your change to UI and the high-cost operation should be fired.

        private DispatcherTimer _timer;

        private void TextSizeSlider_ValueChanged(object sender, RangeBaseValueChangedEventArgs e)
        {
            if (_timer != null) _timer.Stop();

            _timer = new DispatcherTimer();
            _timer.Interval = TimeSpan.FromSeconds(0.5);
            _timer.Tick += _timer_Tick;

            //Remember to start the timer
            _timer.Start();
        }

        private async void _timer_Tick(object sender, object e)
        {
            await BlurImage();
            _timer.Stop();
            _timer.Tick -= _timer_Tick;
        }

        private async Task BlurImage()
        {
            //Do your high-cost operation
        }