There's unfortunately not much we can do about .NET's own first chance internal exceptions occurring when we cancel requests. The main problem is that the Visual Studio debugger cause significant slow down monitoring these, and Microsoft has not been willing to address it.
We tried also not cancelling requests while the debugger is attached, but that causes separate performance issues because we might be loading way more tiles than you ever need.
Rest assured this is not an issue when running without the debugger attached, and you'll see much better performance when not debugging, and your users won't be affected.
