Running PHP without extension without using mod_rewrite?

Using Apache 2.2 and PHP 5, what's the best way to run PHP without the .php extension? For example, I have a script called app.php and I like to invoke it as:

http://example.com/app

Please notice that I still want to keep the .php extension to the file and I don't have mod_rewrite. Don't want use index.php either because it requires too many directories.

I did find one way by adding this to my .htaccess,

AddHandler server-parsed .php
SetHandler application/x-httpd-php
AddHandler application/x-httpd-php .php

The page runs a little slower by using this. I suspect it invokes SSI on every PHP page. Wonder if there are any better ways to accomplish this.