DX11.1 has "some optimizations" that the game can utilise so it tangibly "improves CPU performance" in the game's rendering. DICE has also blown socks off with Frostbite 3.
Seriously, there are hundreds of socks washing up on shores. Fact. That's thanks to the great improvements to Frostbite 3 like dynamic environment destruction.
Don't like that tree? Grenade! It's all part of DICE wanting to let the Battlefield 4 maps slowly but surely feel the scars off conflict as players rampage over them trying to secure objectives. PC gamers have experience the 'it's exclusive to Win #' before with DirectX 10 for Vista, which proved absolute rubbish after 'code enthusiasts' wormed it onto XP.
"We use DX11.1, there are some optimizations in it (constant buffer offsets, dynamic buffers as SRVs) that we got in to the the API that improves CPU performance in our rendering when one runs with DX11.1. This will be in BF4," Johan Andersson on NeoGAF.
Battlefield 4 releases on PC, Xbox 360 and PS3 October 29th in the US, November 1st in EU. Tablets and browsers can act as 'second screens' with the new proposed Battlelog, DICE reveals in a.