People automatically assume that a compiled application will ALWAYS run faster than an interpreted application. While that's generally true, (C# code will almost always run exponentially faster than VBScript), you have to look at the other dependencies that exist and the environment in which the application is run.
In reality, most of the time there's a negligible difference in a simple web application where you're requesting a web page, grabbing it's associated data from a database and then returning it to the browser. Requesting and returning data from the database probably consumes at least 60% of the processing of the page, another 30% is the web server creating the response.
Example, a poorly designed SQL query will slow down your app exponentially more than the chosen language you're using. Remember, it's all about the algorithm!
Trying to be objective here, but I've noticed only negligible difference in returning the same data to the same web page with ASP.NET MVC with C# and ASP. I think you'd see the same results with Spring MVC or PHP, or even ASP.NET MVC with Visual Basic.
That said, I would prefer to use ASP.NET MVC everytime because it gives me the option of using asynchronous controllers and asynchronous actions. I also like to design an application with meaningful objects. It's impossible to do ASP with OOP unless your writing the back end in C++ with ActiveX, which is an ugly solution for modern applications.
ASP doesn't lend itself well to SOC (Separation of Concerns), so most ASP apps resemble a kitchen sink with a weeks worth of dirty dishes.