This goes out to all the folks who tell me that ever since they switched to VS 2005 - the time it takes to build their solution is very very long when talking about web projects. Stop blaming Resharper, folks.
Here's what Scott Guthrie has to say about this:
Keep the number of files in your /app_code directory small. If you end up having a lot of class files within this directory, I'd recommend you instead add a separate class library project to your VS solution and move these classes within that instead since class library projects compile faster than compiling classes using the /app_code directory.