Carl is a fervent supporter of VB.NET and dispels all sorts of myths about the language. Carl told Jeff he didn’t agree, but didn't start a debate. Jeff commands a great deal of respect in the .NET community, as well he should, but I think the truth is somewhere in the middle.
I don’t think the C# code from a competent, professional programmer would show a noticeable difference when compared to the performance of the same implementation written by a competent pro in VB.NET. When it comes to the hobbyist who doesn’t know what “option strict” does, (and doesn’t care) however, this is where you see the spread.
About one year ago I met a pharmacist who wrote an application in ASP.NET. The application tracked drug-drug interactions for patient safety. It was a great implementation of the pharmacist’s domain knowledge. The application worked. Would I have shrink-wrapped the code and put up for sale? No. Was it scalable? No – but, the point is, this fellow was putting his expertise to work, and his expertise wasn’t in building a scalable web site.
If someone put this application through a stress test, they might conclude that the entire .NET platform isn’t scalable. Just like political sound bites – you sometimes have to put a piece back into context before making a judgment. Perhaps this perceived performance difference isn’t really because of the different compilers, but because there is a significant percentage of VB.NET developers who don’t change the default setting of option strict (off by default). Late binding is a drag.
I do think there will be a divergence in the future between C# and VB.NET if VB.NET continues to layer higher levels of abstraction on top of the base class library (like the My keyword in 2005). As long as you know the underlying framework, it still shouldn’t matter much in the time trails.