Assembly: System.Web (in system.web.dll)
The CompilationMode enumeration values indicate whether a page or control should be compiled at run time. When no compilation mode is specified, the default value is Always. Setting a page to never compile using the Never attribute will increase performance by disqualifying the specified page in the compilation process. To define a page-specific CompilationMode attribute that specifies an .aspx, .ascx or .master file should not be compiled at the page level, you can use a directive like the following:
<%@ page compilationMode=”never” %>
The compilation mode can also be specified in configuration files. The PagesSection configuration section object identifies page-specific configuration settings. The pages configuration section element can be declared at the machine, site, application, and subdirectory levels of the configuration files.
If the CompilationMode is set to Never and a page contains a script block or code construct that requires compilation, ASP.NET will return with an error and the page will not run.