asp.net remove unused httpmodules

Question

I am looking at the performance suggestions lots of pages have about asp.net. Specifically the remove unused httpmodules part:

    <httpModules>
  <add name="OutputCache" type="System.Web.Caching.OutputCacheModule"/>
  <add name="Session" type="System.Web.SessionState.SessionStateModule"/>
  <add name="WindowsAuthentication" type="System.Web.Security.WindowsAuthenticationModule"/>
  <add name="FormsAuthentication" type="System.Web.Security.FormsAuthenticationModule"/>
  <add name="PassportAuthentication" type="System.Web.Security.PassportAuthenticationModule"/>
  <add name="RoleManager" type="System.Web.Security.RoleManagerModule"/>
  <add name="UrlAuthorization" type="System.Web.Security.UrlAuthorizationModule"/>
  <add name="FileAuthorization" type="System.Web.Security.FileAuthorizationModule"/>
  <add name="AnonymousIdentification" type="System.Web.Security.AnonymousIdentificationModule"/>
  <add name="Profile" type="System.Web.Profile.ProfileModule"/>
  <add name="ErrorHandlerModule" type="System.Web.Mobile.ErrorHandlerModule, System.Web.Mobile, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
  <add name="ServiceModel" type="System.ServiceModel.Activation.HttpModule, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
</httpModules>

There are bunch of HTTP modules listed here and I am quite positive not all of them are being used by your application. Removing unused HTTP module can definitely give slight performance boost as there would be less work to be performed. Suppose one doesn’t needs Windows authentication in application. To remove the inherited setting, under httpModules section in your web.config application add a remove element and specify name of the module that isn’t required. Example:

<httpModules>
        <remove name="WindowsAuthentication" />
  </httpModules>

Does anyone know where there is a description of what each does, some are obvious but not all, I have serached for quite a while on google.

Answer 1

Comment from ScottGu about this, via Mads Kristensen's blog.

https://www.madskristensen.net/blog/remove-default-http-modules-in-aspnet/

In general you can get some very small performance wins using this approach - although I'd probably recommend not doing it. The reason is that some features of ASP.NET (forms auth, roles, caching, etc) will of course stop working once you remove the modules they depend on. Trying to figure out why this has happened can often be confusing.