WPF too slow?

I'm just looking for a new VSE (= Visual-Control-Element)-design. Using DirectX will propably be overdone but WPF is too slow in a first approach showing 10 signals with 1000 line-segments per Polyline. The overhead is truely too big. So I googled a bit and found a comment of Marco Zhou (Zhou Yong) who proposes using a WriteableBitmap for WPF-GDI-access. Unfortunately, this throws away all the cool stuff of an UIElement, but who needs databinding a static signal anyway?

Using the aforementioned technique, my sample runs at least as smooth as SOMNOlab :)

Now let's try to put some UIElement-biosignal-events atop of it and the weekend is near ^^