AOLserver provides a parser that transforms ADP file into Tcl files. When the templating system first encounters a template pair (TCL+ADP files), it compiles the ADP file into Tcl, and appends that to the TCL script (that sets the datasources, or Tcl vars, used within the ADP file).

It then compiles the resulting Tcl script into Tcl bytecode, and causes that to be cached as well.

Future HTTP requests for the template simply execute the cached bytecode. The only overhead is a simple timestamp check to ensure that the cache represents the latest version of the template (it does this so that changes to the template are immediately reflected in the HTML delivered in response to HTTP requests).