It is much slower for me to build a WizBang program than to fire up vim and write some code. I'm not sure if visual programming could ever be faster than a text editor, as a visual block (in WizBang anyway) usually corresponds to one or two lines of actual code.
But speed is not the point at all in WizBang. The point is to present a clean and simple environment in which beginners can build real programs without having to type more than variable names. I feel it is a much easier way to introduce programming than having someone install Visual Studio and writing a hello world program.