I've actually found ambient occlusion is a terrible drain on any card. It seems to be about a 20-50% performance hit in many games for a very modest improvement in graphics quality. For me, that puts it squarely in the "people with SLI setups get to use this to justify their expense" category. 
Admittedly, I've not put a lot of effort into playing with ambient occlusion settings across multiple games, but the experiences I have had have not been positive.
For me, EQ2 runs quite well on high graphics settings with Shader 3 on and a fast CPU. Because of how SOE built the game, it's highly CPU-bound and uses very few cores. SOE bet on the wrong horse in the hardware development race, and it shows. That said, my performance in EQ2 easily bests that of FFXIV on equally high settings. Now, given your anecdotal evidence and my anecdotal evidence, I wonder if the issue is driver or rendering path related. Champions, for instance, is known to perform better on ATI than nVidia hardware (especially with shadows enabled), and for a while after release, it suffered serious performance issues on 200 and 400 series GPUs. Even now, it suffers from graphical artifacts on 400 series cards. If SE hasn't gotten to optimizing for different cards yet, that could explain the differences in performance and gives me hope we'll see them fixed.
Admittedly, I've not put a lot of effort into playing with ambient occlusion settings across multiple games, but the experiences I have had have not been positive.For me, EQ2 runs quite well on high graphics settings with Shader 3 on and a fast CPU. Because of how SOE built the game, it's highly CPU-bound and uses very few cores. SOE bet on the wrong horse in the hardware development race, and it shows. That said, my performance in EQ2 easily bests that of FFXIV on equally high settings. Now, given your anecdotal evidence and my anecdotal evidence, I wonder if the issue is driver or rendering path related. Champions, for instance, is known to perform better on ATI than nVidia hardware (especially with shadows enabled), and for a while after release, it suffered serious performance issues on 200 and 400 series GPUs. Even now, it suffers from graphical artifacts on 400 series cards. If SE hasn't gotten to optimizing for different cards yet, that could explain the differences in performance and gives me hope we'll see them fixed.
The Freelance Wizard
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((about me | about L'yhta Mahre | L'yhta's desk | about Mysterium, the Ivory Tower: a heavy RP society of mages))
Quality RP at low, low prices!
((about me | about L'yhta Mahre | L'yhta's desk | about Mysterium, the Ivory Tower: a heavy RP society of mages))
