I was at a Microsoft conference and the MS employees stated that C# is up to 8% faster than VB.NET. So if this is a myth, it was started by the people that work at MS. If I can find the slides that state this I would post them, but this was when C# just came out. I think that even if it was true at one point in time, that the only reason for one to be faster than the other is how things are configured by default like ShuggyCoUk said.
