Install WP Super Cache
Search WP Super Cache in the WordPress dashboard, install it, activate it and enable the caching in the plugin admin page.
Enable OPcache in PHP
OPcache improves PHP performance by storing precompiled script bytecode in shared memory. The need for PHP to load and parse scripts on each request is not needed if the bytecode has been cached. OPcache is bundled with PHP 5.5.0 and later.
You can use a small php script to check whether the Opcache is working:
<?php phpinfo(); ?>
Inside of WordPress, you do not need to do any special configuration to make OPcache run for WordPress.
Optimize HTML pages, scripts and CSS files
Autoptimize is a great plugin that can aggregate, minify and cache scripts and styles, injects CSS in the page and minifies the HTML code. There are quite a lot options to tune to make it work for your sites.
With all these plugins and tools, WordPress can be much accelerated. Enjoy the boosted performance of WordPress now!