iis 7 - ASP.NET Intermittent lag before Application_BeginRequest() -

I am using ASP.NET MVC2. In debug mode, a delay of 5-10 seconds before HttpApplication_BeginRequest (), every other request on the server is killed in Global ASX

This is actually every other request it is always faster in release mode But this is causing me problems in testing things in debug mode. I looked at the call stack but the only thing before HttpApplication_BeginRequest () is "external code", so I can not tell what is happening. How can I find out how to start this gap in the pipeline? Thank you.

Does ASPNAT recycle an app domain in every 15 hits? I was once in a situation where I realized that due to the wildcard IIS mapping, all the resource calls on the page (such as script, image etc.) were going through ASP.Net SpaceFundler and thus contributing to 15-hit count. Were there. Does this make any sense?