From the mailing list (by Tom Auinger):

I just found that the Zend_Controller_Router_Interface class includes the Zend_Controller_Front class on line 26 (in ZF 1.0.3):

require_once 'Zend/Controller/Front.php';

However, this class is never used within the interface.

Removing this include would increase performance when using the router interface without the front controller.

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Additionaly:

Route interface should have an additional method:

public static function getInstance(Zend_Config $config);

And then Module Router needs some additional require statements:

Zend_Controller_Request_Abstract Zend_Controller_Dispatcher_Interface