wordpress import csv finish order

Question

I have a method to read a csv file with one column this is used to set order as completed. but whenever I have more than 20 rows it takes forever to load, the file isn t that big so I am surprised it takes that much time

here is the method used to read the csv

function read_csv()
    {
        $fileName = $_FILES["file"]["tmp_name"];
        $row = 1;
        echo '<pre>';
        if (($handle = fopen($fileName, "r")) !== FALSE) {
            while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
                if ($row == 1) {
                    $row++;
                    continue;
                }   // continue is used for skip row 1
                if (strlen(trim($data[0]) >= 4)) {
                    $order = wc_get_order(trim($data[0]));
                    if (!$order) {
                        echo $data[0] . " Pas de commande<br />";
                    } elseif (!Admin::isStaging()) {
                        $order->update_status('completed', 'order_note');
                        echo $data[0] . " Completed<br />";
                    } 
                }
            }
            fclose($handle);
        }
        echo '</pre>';
    }