Horrible WPF performance!

Question

Why am i using over 80% CPU when just hovering some links? As you can see in the video i uploaded: http://www.youtube.com/watch?v=3ALF9NquTRE the CPU goes to >80% CPU when i move my mouse over the links.

My style for the items are as follows

    <Style x:Key="LinkStyle" TargetType="{x:Type Hyperlink}">
        <Style.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Foreground" Value="White" />
            </Trigger>
        </Style.Triggers>
        <Setter Property="TextBlock.TextDecorations" Value="{x:Null}" />
        <Setter Property="Foreground" Value="#FFDDDDDD"/>
        <Setter Property="Cursor" Value="Arrow" />
    </Style>    

Why?

Answer 1

No need to wonder - use XPerf and find out. The video on the topic given at PDC09 is excellent, you'll be up and running quickly.

Answer 2

Hyperlink is your own type, right?

I tried applying your style to a TextBlock instead and could not get CPU to go over 5%, so maybe something is going on inside Hyperlink when one of these properties change. Try to isolate which property is causing the CPU to spike.

Answer 3

I have had a similar issue with styles in my application. With out seeing the whole xaml file of the UI, I would ask if you are using any Bitmap Effects, as these will cause issues with the CPU performance going up. If you are, I recommend not using them and instead used the optimized effect options or use the shader library support in WPF to apply any effects you are looking for.

With my example I had an Element with a drop shadow bitmap effect and was able to switch it to the drop shadow effect, got the desired effect and CPU was not hit. When I had the bitmap effect, it was actually redrawing the whole rectangle region that the effect was on, so when I had a blinking cursor it would redraw every child control from the parent that had the Bitmap effect applied in it.

If you are not using any effects, than I recommend looking at your visual tree and see if it is heavy with UI elements or finally and sometimes the most over looked, check your triggers and/or events that you may have defined for the over state of the Hyperlink type that is being displayed could be something hanging out there that is causing some issues.