IIS - Creating a new thread for thread pooling performance

In my book "MCTS Self-Paced Training Kit (Exam 70-515):Web Applications Development with MS .NET Framework 4, it states:

(The context is IIS 6 and 7)

Thread pooling can be tricky. When implementing asynchronous handlers and webpages, use a performance testing tool to verify performance under a heavy load. Sometimes the overhead introduced by asynchronous programming can offset the benefits. Whether performance improves depends on many aspects of the application and web server configuration. One sure way to get performance g开发者_JS百科ains is to create a new thread. There is only one Common Language Runtime (CLR) thread pool per AppDomain, so you must be sure to not just consume the same threads ASP.NET would be using. Instead, create your own.

How do I create a new thread without reusing the same threads in the current thread pool?