Гугловский web.dev выдает рекомендации по оптимизации сайта. Бэкендна Java (node.js)
Всего 13 позиций:

1. Efficiently encode images
2. Serve images in next-gen formats
3. Avoid multiple page redirects
4. Buttons do not have an accessible name
5. Ensure the viewport doesn't disable text scaling and zooming
6. Eliminate render-blocking resources
7. Properly size images
8. Reduce server response times (TTFB)
9. Does not use HTTPS
10. Browser errors were logged to the console
11. robots.txt is not valid
12. Tap targets are not sized appropriately
13. Background and foreground colors do not have a sufficient contrast ratio

Сам сайт - vpnm.ru