Best way to loop requests to a PHP API

Question

I am working with an api in which I send a CURL request and it returns me a json the problem is that if I loop in PHP the server hangs and the processing is very slow, a solution I found was to separate the page that makes the request and to make a request at a time via ajax, but in this case after 3 thousand times the server also hangs. I need some idea so I can make at least 20,000 requests faster and without crashing the server. Anyone have any idea?

Part of the code:

public function put($path, $body = null, $params = array()) {
        $body = json_encode($body);
        $opts = array(
            CURLOPT_HTTPHEADER => array('Content-Type: application/json'),
            CURLOPT_CUSTOMREQUEST => "PUT",
            CURLOPT_POSTFIELDS => $body
        );

        $exec = $this->execute($path, $opts, $params);

        return $exec;
    }

while($i<$t){
    $price = $arr_precos[$i];
    $mlb = $arr_ids[$i];
    $i++;

    $edit = '/items/'.$mlb;
    $body = array("price"=>$price);
    $response = $meli->put($edit, $body, $params);
}

The above code executes the loop, the other way I found using the same code but without the loop by PHP, I loop requests to a PHP file with this code via ajax.

Note. All request and data processing is done in PHP + MYSQL