Hi,
By default, the theme is very good optimized for each type of devices. The theme is developed in most high optimized way.
All CSS and JS Files are minified and the Images are loaded with minimal size for each type of devices.
You can add some additional optimizations:
1. Use a cache plugin with special features for static file. But that will not increase considerable the load speed because the files are minified.
2. Use a special plugin to optimize de image file size ( less quality small file size ). That also not will improve considerable the speed load.
3. Use a special service like cloudflare.com
If you have a slow speed load then the problem is with the server configuration ( hardware and software ).