According to Charlie at Semiaccurate, AMD's upcoming HD8000 Sea Island GPU's won't be bringing the same kind of performance jump as previously expected.

AMD HD8000 Sea Islands Not as Fast as Thought?

Last month, specifications of both the HD8800 and HD8900 series graphics card were leaked based on the latest 28nm Sea Islands architecture. The specifications showed that users would gain a massive performance improvement with Sea Island cards over Southern Island however now its being reported that AMD won't be delivering the same kind of leap as expected. AMD claimed to its AIB's that a 30% increase was expected with Sea Islands however Semiaccurate's sources suggest that 15% is a much more accurate number.

Another reason for this could be AMD's revenue which fell by 10% in the third quarter of 2012 which increases burden of siliconmanufacturingfor the upcoming cards. Hence rather then an increased stream processor count, AMD would be focusing on process improvements and algorithmoptimizationswith the HD8000 Sea Island GPU's . Hopefully, Volcanic Islands and Pirate Islands won't be as muchdisappointingas Sea Islands is currently looking.