Code Snippets for WordPress and WooCommercce speed up are snippets which can be easily imported into the code snippets plugin.
For other useful code snippets for WordPress. https://github.com/senlin/Code-Snippets
You will need to install and active Code Snippets plugin on the site you want to import and use those code snippets on. Look for the Snippets admin menu, when viewing from wp-admin. So from Snippets > Import, select the JSON or XML file you want to import, then click on the Upload file and import button. Then from Snippets > All Snippets, you can see all, active and decativated snippets.