Prima have numerous features improving the speed of Magento greatly
- All CSS and JS files are combined and minified automatically
- All the non dynamic blocks (such as the MegaMenu, Revolution Slider, The footer, The product carousels) are cached and the HTML is minified
- All the product carousels have lazyload feature to postpone the load of the images
- Extensive use of AJAX allows parts of the website to be loaded later, when needed
- Backend control for the image compression level. Choose between speed and image quality.
Check here the Pingdom.com test
With time for the first bite at ~160 milliseconds and full page load time at ~600 milliseconds, Prima is faster than any other Magento theme on ThemeForest! Nobody loves slow websites, especially when it comes to e-commerce.