Is it advisable to switch from a custom MVC framework to established frameworks like Yii, Zend, or CakePHP for improved efficiency and sustainability?

Switching from a custom MVC framework to established frameworks like Yii, Zend, or CakePHP can be advisable for improved efficiency and sustainability. Established frameworks have been tested and optimized over time, offering better performance, security, and scalability. Additionally, using a popular framework can make it easier to find support, documentation, and developers familiar with the technology.

// Example code snippet demonstrating how to switch from a custom MVC framework to Yii framework

// Custom MVC framework code
class CustomController {
    public function indexAction() {
        // Controller logic
    }
}

// Yii framework code
class YiiController extends \yii\base\Controller {
    public function actionIndex() {
        // Controller logic
    }
}