I have a map which loads markers via ajax on various/numerous map events. Currently, I define a custom page callback for my hook_menu() item which prints my json/js.

Since my page callback does not return any content and only prints content, Drupal does not render the full template, menu, etc, and thus allows me to return a page with only my JavaScript.

Although this does work, I believe that Drupal still fully bootstrapping, which means it is adding a lot of overhead I would like to drop.

I've been looking at High-performance JavaScript callback handler, which boasts itself as a "High-performance JavaScript callback handler" and which, in short, looks as though it offers a js.php to compliment index.php to direct your requests to and customize/limit/optimize the bootstrapping Drupal does by default.

Unfortunately the js project doesn't have a D7 release yet (petition for one here), which leads us to the beginning...

What is the fastest way to implement an Ajax callback in Drupal?