Smarty cache

Cache stores recently used information so that it can be quickly accessed at a later time in order to run more efficiently, thereby improving performance.

Smarty is PHP template engine. With Smarty, you are able to separate business/program logic from your GUI design (theme or template).

PrestaShop utilizes the Smarty engine so that you are able to switch/change your PrestaShop theme easily. But in order to make your theme file work, it has to be compiled into native PHP code before your web server can render the page HTML contents to your browser client. Compiling theme files will reduce your server performance. In order to minimize the performance hit, PrestaShop uses Smarty functions so that the compilation is done only at the first execution of the theme files.