Could not figure out why things were taking so long so put Console.WriteLine(s) to show what is happening (so you can see it.
When I set the ItemsSource I get:
[DOTNET] Set full name to Dan O'Rourke
[DOTNET] Set full name to Kelly Sutherland
[DOTNET] Set full name to Julien Fournier
[DOTNET] Set full name to Libor Suchanek
Then as it handles the Bindings I get:
[DOTNET] Get full name to Dan O'Rourke
[DOTNET] Get full name to Dan O'Rourke
[DOTNET] Get full name to Kelly Sutherland
[DOTNET] Get full name to Kelly Sutherland
[DOTNET] Get full name to Julien Fournier
[DOTNET] Get full name to Julien Fournier
[DOTNET] Get full name to Libor Suchanek
[DOTNET] Get full name to Libor Suchanek
While a user might not notice if the list is not too long this is a definite problem.