Currently I’m working on a web application project that also uses a WCF service for some operations. We are a big fan of using ALT.NET and are using Castle Windsor to do IoC (Inversion of Control)/Dependency Injection. The problem we were having was the small delay to start up the worker process in IIS. Which is not much you can do about within IIS. (As far as I know) Except for maybe making a wake up service that calls a simple method every x minutes. Just to keep the worker process alive.