动态调整WPF TextBlock大小时的性能不佳

I'm currently working out the layout of a WPF Application and seem to have it a bit of a snag in the layout of one of my controls. This control is a dynamically sizing, so it should fit the size of the viewport it's a part of. The problem I'm running into is a very visual problem, so I'll do my best to describe it. Here's what it looks like at the moment:I'm currently working out the layout of a WPF A