How to use the execute method for friends.get Vkontakte Api?

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I use the following php code to get the id of friends:

$resp = file_get_contents('https://api.vkontakte.ru/method/friends.get?user_id='.$_GET["userid"].'');
$data = json_decode($resp, true);
$myfriends = implode(",", $data[response]);

The problem is that I need to complete about 200 such requests and the process is very long. It is said that queries can be optimized using the execute method.
Can you please tell me how to rewrite my code under execute?