We are about to embark on a large enterprise application. I am seriously considering using ASP.NET MVC because:
Have used WebForms for years and never liked them. Now use Asp.Net MVC for some years and this is so much better. Certainly woud recommend MVC.
Asp.Net MVC has an excellent architecture and is open source. So if you would identify bottelnecks in the http processing chain you could fix it. Most time you would be able to fix performance issues using one of the many extension points provided by Asp.Net MVC, like Binders as an example.