I have discovered that during the high number of users (20-30k within 20-30 seconds) web application made in ASP.NET MVC2 cause bottleneck when
on the return View(); view name is not specified.

public ActionResult Index() {
...
return View(model); // causes 39 s page load
}

public ActionResult Index() {
....
return View("Index",model) // reduced the page load to 0.2 s
}

This problem occurs only when we deal with high user concurrency.

I described the whole problem on my blog.


http://arturito.net/2011/10/24/asp-net-mvc2-in-the-web-farm-slow-page-load-with-high-traffic-where-is-the-bottleneck/