Black Joomla
Free Joomla Template Joomla Extensions
XT Adaptive Images is the best extension to generate responsive images. It packs Adaptive Images + HTML's new responsive image attributes (srcset and sizes) + Lazy Load + CDN in a single plugin.
Joomla have a native cache and Gzip compression system, that's a good start.
Speed Cache comes over as a natural improvement of the Joomla page cache system with a lot of performance, compatibility and features enhancement.
