Benchmark Results: DirectX 11 Versus DirectX 9
Now we will use the DirectX 11 option on the Radeon HD 5000-series cards. We've seen a subtle increase in visual fidelity from the DirectX 11 code path, so will this be accompanied by an appropriately low performance?
The answer is no. Enabling DirectX 11 has a massive impact on performance. The Radeon HD 5750 and 5770 can easily handle the high 2560x1600 resolution in DirectX 9 mode, but in DirectX 11 mode things become very choppy.
On the plus side, even though performance has dropped, the Radeon HD 5850 and 5870 continue to deliver smooth performance at high resolutions. And it is notable that now the Radeon HD 5850 CrossFire solution doesn't lose much in the way of minimum frame rates while the single Radeon HD 5870 demonstrates a huge performance hit when DirectX 11 is enabled.