Joomla, like WordPress can be painfully slow when a site gets busy. To combat this, we strongly recommend that you enable Joomla's built in caching. When using caching, Joomla 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 Joomla's built in caching
It only takes a minute to enable Joomla's built in caching. You need to go to your Joomla site and click on the 'Site Administrator' section. Log in as the Administrator account that you have set up. Once at the Administration control panel, hover your mouse over the 'Extensions' menu and select 'Plugin Manager'. Type 'cache' into the Filter field and click the 'Search button', then click on the red circle in under the 'Status' column of the 'System - Cache' plugin. Caching is now enabled.
With caching enabled, changes that you make to your site may take a while to display on your site. If you are adding content and want to see it on the site immediately, then you can hover your mouse over the 'Site' menu, go to the 'Maintenance' section and click on the 'Clear Cache' option. Tick the checkbox of all of the cache groups that you want to clear, and then click the 'Delete' button.