The JSP pre-compilation functionality is used to compile the JSP files contained in a Web application before they are deployed and then generate the class files.

The following figure shows the processing flow when the JSP pre-compilation functionality is used.

Figure 2-4 Processing flow when the JSP pre-compilation functionality is used

Normally, the JSP files contained in a Web application are compiled when the first request arrives for a JSP file and class files are generated from the JSP files. As a result, the response time during the first request for JSP is delayed. If <load-on-startup> is specified in web.xml, the compilation time becomes the starting time of the Web application, and therefore, the response time when the first request arrives for JSP can be shortened. Web application, however, will take a long time to start.

When you use the JSP pre-compilation functionality, the response time when the first request arrives in JSP and the starting time of the Web application can be shortened, since the class files are already generated.