Trying to speed up page loading in BX, what do you say?

Question

1C-Bitrix

Hello! In an attempt to achieve maximum site loading speed, I go through various practices and try to apply them in my projects.
Now my interest fell on the delayed loading of scripts, which can be seen on the Lamoda website, in general, there are many interesting solutions that allow you to load the page with incredible speed. For example, pictures are compressed in webp. But now I'm interested in lazy loading of scripts. In fact, it will not be difficult to implement this mechanism, it is enough to use a couple of lines of JS:

var script = document.createElement('script');
script.src = src;
document.body.appendChild(script);

If you look for various anti-examples of loading pages, then you can cite the Eldorada site as an example.
In an attempt to implement something similar to lamoda, I tried to sketch the following code, and I would like to know your opinion

// Вешаем обработчик события и получаем код страницы
$eventManager->addEventHandler("main", "OnEndBufferContent", "deferredLoading");

// Наш обработчик
function deferredLoading(&$content){
    // Паттерн который будет отделять названия файла
    $getPattern = '/src=".*.js.*"/';

    // Список паттернов по которым будем искать нужные нам скрипты, в данном примере ищем core_db.js и loadext.js
    $arScripts = [
        ["del" => '/<script.+?src=".+?bitrix\/js\/main\/core\/core_db[^"]+"><\/script\>/'],
        ["del" => '/<script.+?src=".+?bitrix\/js\/main\/loadext\/loadext[^"]+"><\/script\>/']
    ];
    // Ищем и находим
    foreach ($arScripts as &$script){
        preg_match($script["del"], $content, $res);
        if($res[0]) {
            preg_match($getPattern, $res[0], $res);
            $res = str_replace("src=", "", $res);
            $content = preg_replace($script["del"], "", $content);
            $script["script"] = $res[0];
        }
    }
    unset($script);

    // Добавляем найденные скрипты
    $strScr = '';
    for($i = 0; $i < count($arScripts); $i++) {
        $strScr .= ($i < count($arScripts)-1) ? "".$arScripts[$i]['script'].",\n " : "".$arScripts[$i]['script']."";
    }
    
    // JS Скрипт, который будет подключать все это дело 
    $string = "
    <script>
    function fastLoad() {
        var scripts = [
           $strScr
        ];

        load = function (src) {
            var script = document.createElement('script');
            script.src = src;
            document.body.appendChild(script);
        };
        for (var i = 0; i < scripts.length; i++) {
            load(scripts[i]);
        }
    }
    fastLoad();
    </script>";
    // Ставим в нужном месте в шаблоне тег, вместо которого вставится наш JS код
    $content = str_replace("<!-- add_js -->",$string, $content);
}

Well, that's all, in this way you can drag all the Bitrix scripts, and not only them, to the very bottom, allowing the photos in the catalog to load first, and only then them.
It remains only to understand which scripts are worth transferring and which are not.