R – How to apply an effect to a Border but not to its contents in WPF

I have a WPF application that has a 3rd party data grid with a border around it. I've used the DropShadowEffect to put a shadow behind the border, but this seems to affect performance somewhat (not nearly as much as a BitmapEffect, but still noticeable) and makes the font rendering fuzzy. Is there a way to somehow apply the effect to the border, but not its contents?

I tried setting the Effect on the contents to {x:Null}, but that didn't help.

Here is a sample app I came up with. It puts a shadow behind the border, but it also puts a shadow behind each line of text. I want the shadow behind the border, but not the text.

<Window x:Class="WpfEffectTest.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <Grid>
        <Border BorderBrush="Black" BorderThickness="10" CornerRadius="5" Margin="25">
            <Border.Effect>
                <DropShadowEffect BlurRadius="10" ShadowDepth="5" />
            </Border.Effect>
            <StackPanel>
                <TextBlock>This is some text</TextBlock>
                <TextBlock>This is some text</TextBlock>
                <TextBlock>This is some text</TextBlock>
                <TextBlock>This is some text</TextBlock>
                <TextBlock>This is some text</TextBlock>
                <TextBlock>This is some text</TextBlock>
            </StackPanel>
        </Border>

    </Grid>
</Window>