Chris Angelini likes to use the Going Hunting mission for testing Battlefield 3 performance. I'm partial to Thunder Run's opening sequence, though. It's slightly more demanding as a result of the sand that gets kicked up by the tanks.
On one end of the spectrum we start with Low quality, establishing that the Radeon HD 7670M only runs smoothly at 1280x720. The older GPU achieves almost 36 FPS on average at 1600x900, but minimums take that resolution as low as 25 FPS.
In comparison, the Radeon HD 8790M delivers between 115 and 125% more performance. AMD's GCN architecture, coupled with aggressive clock rates and plenty of memory bandwidth, combine to drive an average of nearly 60 FPS.
At the other end of the spectrum, AMD's Radeon HD 8790M continues to manage playable frame rates at 1280x720. The situation starts to deteriorate at 1600x900, and 1920x1080 really isn't accessible.
But even at 26 FPS, the 8790M handily outperforms the Radeon HD 7670M at 1280x720. Again, it's hard to know if that's a straight-across comparison, given the lack of power data at our disposal. But knowing that these GPUs are intended to serve the same market, it's at least exciting to see how much more potential will be made available in the year to come.