Why is aspnet_compiler.exe so slow (and can it be made any faster)?

Question

During our build process we run aspnet_compiler.exe against our websites to make sure that all the late-bound stuff in ASP.NET/MVC actually builds (I know nothing about ASP.NET but am assured this is necessary to prevent finding the failures at runtime).

Our sites are fairly large in size, with a few hundred pages/views/controls/etc. however the time taken seems excessive in the 10-15 minute range (for reference, this is longer than it takes the entire solution with approx 40 projects to compile, and we're only pre-compiling two website projects).

I doubt that hardware is the issue as I'm running on the latest Quad core Intel chip, with 4GB RAM and a WD Velociraptor 10,000rpm hard disk. And part of what's odd is that the EXE doesn't seem to be using much CPU (1-5%) and doesn't seem to be doing an awful lot of I/O either.

So... is this a known issue? Why is it so slow? And is there any way to speed it up?

Note: To clarify a couple of things people have answered about, I am not talking about the compilation of code within Visual Studio. We're using web application projects already, and the speed of compilation of those is not the issue. The problem is the pre-compilation of the site after these projects have already been compiled (see this MSDN page for more details) as part of the dev build script. We are performing in-place pre-compilation, not copying the files to a target directory.

Answer 1

I don't have any specific hot tips for this compiler, but when I have this sort of problem, I run ProcMon to see what the process is doing on the machine, and I run Wireshark to check that it isn't spending ages timing-out some network access to a long-forgotten machine which is referenced in some registry key or environment variable.

Answer 2

1. Compiler should generate second code-behind file for every .aspx page, check
2. During compilation, aspnet_compiler.exe will copy ALL of the web site files to the output directory, including css, js and images.

You'll get better compilation times using Web application project instead of Web site model.