Slowness in web applications might be result of a wide range of underlying issues in the application code, client side, network or web server. Therefore, system administrators should analyze IIS logs, Failed Request Tracing logs, dump files, and HTTP.SYS logs to narrow down the issue.
HTTP.SYS
IIS binding limit (401.2 Windows Authentication error)
IIS can perform Windows Authentication to allow your users to a web application. This authentication process can take place on the user-mode (IIS worker process) or kernel-mode (HTTP.SYS).