Only load the routes you want based off of URI params

index.php

<?php

// Stupid dirty example of how to load only the routes you want.
$app->hook('slim.before.router', function() use ($app) {
    $uri = $app->request()->getResourceUri();
    $params = explode('/', substr($uri, 1, strlen($uri)));
    if (file_exists(APP_ROOT . '/app/routes/' . $params[0] . '.php'))
        include APP_ROOT . '/app/routes/' . $params[0] . '.php';
});