You get sloppy and write something like this:

D'oh.

One common ASP.NET performance tip is to remove any HttpModules that your application does not use.  You can take a peek at which modules are loaded by the framework on your behalf by examining the framework's Web.config file, but how do you find out which modules are actually loaded in the current context?

Fortunately, the HttpApplication instance provides a Modules collection that you can loop through:

You can then use the Modules collection create a table like this:  

And boom, there you have it: a list of HttpModules that are loaded for the current context.  You can use this information to determine which HttpModules are needed by your application, and which ones you can safely remove.

In Visual Studio 2008, when you add a new Web form to your project, the "using" section of the code-behind contains a lot noise:

You may very well need some of those namespace declarations, but odds are high that you don't need them all.  But which ones can you remove without breaking your page?

Visual Studio has a nice feature called Organize Usings, which you access by right-clicking anywhere in the code-behind page.  The menu looks like this:

When you click on "Remove and Sort", it removes any unused "using"s and sorts those that remain. 

So now, instead of the mess that we had before, we have a much cleaner "using" section in our source code file:

Pretty slick, huh?

Dear fellow coders,

Please don't ever do this:

Love,

Jon