看来，我原来的问题的答案(SL4是否存在固有的内存泄漏?)的确是肯定的！

It appears that the answer to my original question (are there inherent memory leaks with SL4?) is indeed yes!

http://forums.silverlight.net/forums/t/211504.aspx

https://connect.microsoft.com/VisualStudio/feedback/details/649246/usercontrol-resources-memory-leak-silverlight-4-0-60129-0

上面链接中描述的两个泄漏显然已在SL5中修复.

The two leaks described in the links above have apparently been fixed in SL5.