Убираем системные скрипты и стили kernel_main для неавторизованных пользователей

В init.php добавить:

AddEventHandler("main", "OnEndBufferContent", "deleteKernelJs");
AddEventHandler("main", "OnEndBufferContent", "deleteKernelCss");

function deleteKernelJs(&$content) {
    global $USER, $APPLICATION;
    if((is_object($USER) && $USER->IsAuthorized()) || strpos($APPLICATION->GetCurDir(), "/bitrix/")!==false) return;
    if($APPLICATION->GetProperty("save_kernel") == "Y") return;
    
    $arPatternsToRemove = Array(
        '/<script.+?src=".+?kernel_main\/kernel_main\.js\?\d+"><\/script\>/',
        '/<script.+?src=".+?bitrix\/js\/main\/core\/core[^"]+"><\/script\>/',
        '/<script.+?>BX\.(setCSSList|setJSList)\(\[.+?\]\).*?<\/script>/',
        '/<script.+?>if\(\!window\.BX\)window\.BX.+?<\/script>/',
        '/<script[^>]+?>\(window\.BX\|\|top\.BX\)\.message[^<]+<\/script>/',
    );
    
    $content = preg_replace($arPatternsToRemove, "", $content);
    $content = preg_replace("/\n{2,}/", "\n\n", $content);
}

function deleteKernelCss(&$content) {
    global $USER, $APPLICATION;
    if((is_object($USER) && $USER->IsAuthorized()) || strpos($APPLICATION->GetCurDir(), "/bitrix/")!==false) return;
    if($APPLICATION->GetProperty("save_kernel") == "Y") return;
    
    $arPatternsToRemove = Array(
        '/<link.+?href=".+?kernel_main\/kernel_main\.css\?\d+"[^>]+>/',
        '/<link.+?href=".+?bitrix\/js\/main\/core\/css\/core[^"]+"[^>]+>/',
    );
    
    $content = preg_replace($arPatternsToRemove, "", $content);
    $content = preg_replace("/\n{2,}/", "\n\n", $content);
}