This theme comes with a couple of plugin support. Only activate plugins that you need. Deactivate unused plugins.

We recommend using a good caching plugin as well as a script optimize plugin. It will decrease loading time.

You can try these plugins –

1. https://wordpress.org/plugins/wp-super-cache/
2. https://wordpress.org/plugins/autoptimize/
3. https://wordpress.org/plugins/wp-smushit/
4. https://wordpress.org/plugins/wp-sweep/

You can check this detailed tutorial – http://www.wpbeginner.com/wordpress-performance-speed/