↪ Latest builds of the WebKit engine bring great performance improvements when running on MacBooks Pro with Retina screens

WebKit cone

If you have a MacBook Pro with a Retina display and find Safari slow / heavy on it, that's great news: nightly builds recent WebKit (the page rendering engine used by Apple's browser) solved this problem, making everything absurdly smoother by jumping from 20 to 50 frames per second, on average. It is not yet known when this will be incorporated into Safari itself, but it is hoped that it will not take so long. (AnandTech)