In order to maximize the performance, we could have several layer caching when user access the conent.

Block and Page Cache

This the caching built in Drupal. Instead of executing the SQL command, it provide the caching to anonymous user. The configuration stay in configuration / performance.

We could use Clear all cache button or drush cc all to clean that up.

HTTP Header X-Drupal-Cache to see if this cache is HIT.

JS and CSS Cache

We could use drush cc css-js to flush JS cache.

Varnish

It’s a caching HTTP reverse proxy. It will store the anonymous page or static page.

Akamai

It’s the CDN. Akamai provide the API endpoint to flush cache, so it’s possible to integrate the CDN cache flushing in Drupal admin UI.

If the expected result’s not showing up, we could use cache busted to tell it’s related to CDN caching or not.