Compiling JSP files is resource intensive and time consuming. Pre-compiling JSP files before deploying applications on the server will improve application performance. When you do so, only the resulting servlet class files will be deployed.
You can specify to precompile JSP files when you deploy an application through the Admin Console or DeployTool. You can also specify to pre-compile JSP files for a deployed application with the Admin Console under Stand-Alone Instances > server (Admin Server) on the Advanced/Applications Configuration tab.