Gets or sets a value indicating the maximum number of I/O threads per CPU in the CLR thread pool.
Assembly: System.Web (in System.Web.dll)
The value of must be equal to or greater than the MinFreeThreads setting in the httpRuntime configuration section.
You can have some control over the CPU utilization by setting the number of worker threads and I/O threads, using the MaxWorkerThreads property and the property respectively.
The difference between the two types of threads is that the latter are bound to I/O objects, such as a stream or a pipe, and the former are traditional unrestricted threads. For Internet Information Services (IIS) version 6.0 and later, ASP.NET processes requests on worker threads. This is because ASP.NET is integrated within IIS.
These threads are obtained from the process-wide CLR thread pool belonging to an application.
Usually the default values for the allowed threads are sufficient to keep the CPU utilization high. If for some reason your application is slow, perhaps waiting for external resources, you could try to increase the number of threads to a value less than 100.