WPF ListView Very Slow Performance - Why? (ElementHost, or Other Reason?)

I have a Windows Forms app, that has a single ElementHost containing a WPF UserControl... in my WPF, I have a VERY simple ListView:

<ListView Margin="4" ItemsSource="{Binding Notifications}">
    <ListView.View>
        <GridView>
            <GridViewColumn Header="FirstName" DisplayMemberBinding="{Binding FirstName}" />
            <GridViewColumn Header="LastName" DisplayMemberBinding="{Binding LastName}" />
            <GridViewColumn Header="Address" DisplayMemberBinding="{Binding Address}" />
            <GridViewColumn Header="City" DisplayMemberBinding="{Binding City}" />
            <GridViewColumn Header="State" DisplayMemberBinding="{Binding State}" />
            <GridViewColumn Header="Zip" DisplayMemberBinding="{Binding Zip}" />
        </GridView>
    </ListView.View>
</ListView>

If my source has 10 items, the form loads in less than one second. If my source has 1000 items, it takes 7 seconds!!! My timer is ONLY taking the loading into account (not how much time it takes to get the items).

So my question is:

Is using an ElementHost a performance nightmare?

Is WPF DataBinding a performance nightmare?

Is the ListView a piece of crap? (btw, same results with the WPFToolkit's DataGrid)?