Why disable/remove IIS modules when using ASP.NET Core?

Question

Microsoft's ASP.NET Core documentation (https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/modules?view=aspnetcore-2.1#disabling-iis-modules) says

If an IIS module is configured at the server level that must be disabled for an app, an addition to the app's web.config file can disable the module.

but it doesn't explain when/why one would have to disable or remove such a module. Are there specific reasons? Is it recommended to disable any module that doesn't function along with ASP.NET Core?

Answer 1

The whole guiding design philosophy of ASP.NET Core is streamlining your app. ASP.NET Core removes library dependencies that aren't actually used from your build. The whole middleware pipeline exists so that you can include only what you need, etc. This is just one more of thing along those lines.

IIS loads a default set of modules. If you don't actually need those modules for your app, then it's just cruft that adds extra processing to each request. Hence, remove the modules you don't need/aren't utilizing. The goal is to get from request to response in the fewest steps possible, and IIS modules are simply one more of those steps the request has to pass through. That's fine if you need it, but if you don't, you're wasting cycles, resources and time.