After watching this video, I realise there's an extra slab of concrete after the 2nd to last corner for extra run off area, making that part of the track much wider. This completely explains why cars are suddenly faster and why Hamilton and Riciardo and even Webber... are so much faster than all the previous F1 drivers.
The difference is easily more than a second, which explains why the AMG GTS got such an incredible time. To be fair tho. That slab of concrete was there when the SLS black did its lap too though, but it definitely wasn't there back a few seasons back. I can't pinpoint it yet