<UserControl x:Class="MyClass"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:eo="http://schemas.essentialobjects.com/wpf/"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300"
             Unloaded="UserControl_Unloaded" >
    <Grid>
        <eo:WebControl Name="webControl1" Grid.Column="0" Visibility="Visible">
            <eo:WebControl.WebView>
                <eo:WebView LoadCompleted="WebView_LoadCompleted" NewWindow="WebView1_NewWindow">
                </eo:WebView>
            </eo:WebControl.WebView>
        </eo:WebControl>
    </Grid>
</UserControl>

private void UserControl_Unloaded(object sender, RoutedEventArgs e)
{
    if(this.webControl1.WebView != null){ this.webControl1.WebView.Dispose();}
    GC.Collect();
    GC.WaitForPendingFinalizers();
}