WPF应用程序对一些用户来说占用太多CPU

I have a WPF application written in VS2010 Express for .Net 4. Some testers report that the application takes alot of CPU (~80%-100%) whenever the application window is visible and 0% when not visible. This is not the case on my computer, nor on the other computers i have tested. What I see is that it takes a bunch of CPU for the first few seconds after opening the window, but then goes down to a few percent.I have a WPF application written in VS2010 Expr