cache json output or not?

We have an Android App with a large number of users (about 300k) that uses PHP Yii Framework as web-service and Xcache as our cache system.

In the Main page of the app we have some statistics about app and top 6 users to show.

Is this a good way too cache the json output that requested by android every time (for a few hours)?

What is the best way to do that?

My code:


public function actionGetMainStats()

{

    $result = Yii::app()->cache->get('mainStats');

    if($result == null){

        // calculate the mainStats Array

        $mainStat = User::model()->androidMainStats();

        Yii::app()->cache->set('mainStats', $calculatedArray, 100000);

    }


    echo CJSON::encode($mainStats);

}