New article on OdeToCode: Precompilation in ASP.NET 2.0. Here is an excerpt:
Although pre-compilation will give our site a performance boost, the difference in speed will only be noticeable during the first request to each folder. Perhaps a more important benefit is the new deployment option made available by pre-compilation - the option to deploy a site without copying any of the original source code to the server. This includes the code and markup in aspx, ascx, and master files.
It seems the precompile.axd 'magic page' touted as a feature in the early days has slipped quietly into the bucket of dropped features.
Although pre-compilation allows you to deploy a web application without any ASPX files present, this still poses a problem if a request comes in for a directory and you want the request to find a default document for the directory. The 'default document' issue has been a thorn in the side of url-rewriters for quite some time.
If you try to pre-compile to a target directory that already contains a pre-compiled application, the aspnet_compiler will fail with “error ASPRUNTIME: Object reference not set to an instance of an object”. Ugh - unhelpful. Use the –f switch in this case to force an overwrite.