Serialization of Events (+3 C#)
VB.Net implements events differently than C#. As a result, when a VB.Net object that contains events is serialized, by default, its events are serialized too… along with the objects referenced by these events… along with the events referenced by these object.
A great article explaining this can be found here.
I must admit that a couple years ago, I spent a very, very long time tracking down some memory leaks that were caused by this problem. Most of the serialization articles I read were using C#, so they did not mention this issue.
The best way I found to counter it is to create custom events on serializable types. However, this is a lot of extra work, and so the points go to C#.