Many web developers praise Drupal 8 for its excellent performance. Nevertheless, this engine is not efficient enough when serving a massive influx of user requests. In this case, it is not uncommon for expert developers to employ an aid from a caching proxy server. Usual examples of such solutions are Apache and nginx. However, for Drupal, the best choice would be Varnish - a caching server that allows the speeding up of the web page, loading from 10 to 1000 times. This is a more advanced option than the same Apache.
Is Varnish Really Necessary?
read more about it here https://anyforsoft.com/blog/using-varnish-drupal-8