Is the project a web site or web application project? The web site code is compiled on the fly - changes made in App_Code folder make the application restart so the load afterwards should be slower. You mentioned App_Code folder - so it should be web site project. However I have seen web application projects with this folder too (someone created it manually). If it is web application, there should be the Old_App_Code folder. In this case, after each code change you need to build the project e.g. in Visual studio.