Drupal, like WordPress can be painfully slow when a site gets busy. To combat this, we strongly recommend that you enable Drupal's built in caching. When using caching, Drupal pages are cached and stored in a static file for serving future requests directly from the file rather than building the page again from the content database. This hugely improves the responsiveness of the website.
Enabling Drupal's built in caching
It only takes a minute to enable Drupal's built in caching. You need to go to your Drupal site and be logged in as the admin. Once here, click on the 'Configuration' tab at the top. Select the 'Performance' option under the 'Development' section of the configuration page. You need to enable the 'Cache pages for anonymous users' and 'Cache blocks' options. Click the 'Save configuration' button. Disable 'Compress cached pages' at the bottom of the page under the 'Bandwidth Optimization' section.
With caching enabled, changes that you make to your site may take a while to display on your site. The 'Expiration of cached pages' sets how long a cached version of a page can be used before regenerating cached version of the page. A setting of 5 minutes be fine for most sites. If you are adding content and want to see it on the site immediately, then you can use the 'Clear all caches' button to force the cache to be emptied and all of the pages to be refreshed.