Stock vs stock, 2600K has 37% lower single thread runtime in THG benchmark suite that measures single thread efficiency. These are hard facts.
http://www.tomshardware.com/reviews/...0x,3075-8.html

2600K , 8:11
8150, 11:13
673s/491=1.37 or 37% lower runtime. So approx. on average intel 2600K is 37% faster in single threaded tasks. In MT the runtime is just 12% better for 2600K (again stock vs stock).

If we look at the 3960X and normalize for clockspeed,intel achieves 1.5x lower single thread runtime than AMD with FX. Some may think this gap cannot be overcome with any soon to come core but it's not quite the case. What AMD needs to achieve parity with SB-E in single thread runtime? They need a 2 successive IPC jumps of approx 10% each(BD->PD 10%, PD->SR 10%) and they need a clock speed uplift with SR core @28nm to 4.5Ghz/5Ghz stock/Turbo. This would push AMD's single core performance right in the league of SB-E,again stock vs stock: 1.1 x 1.1 x 5Ghz/4.2Ghz~=1.44x. Runtime of SR core in the same same suite THG used would land around 7:48 .

Now to achieve 2 successive IPC jumps of ~10% is very hard and although SR may do it over PD,I doubt PD will be 10% faster than BD. Clock speed uplift on the other hand is possible since not only FX launched on sucky 32nm process from GloFo, both PD and SR will incorporate new technological solutions that will push the clock speed higher. PD (and SR) will have resonant clock mesh,while SR will be done on smaller node (28nm) so there will be some natural power draw reduction,die area reduction and clock speed gain.Pipeline itself is designed for higher clockspeeds so I think AMD knows how high can they clock this thing,provided power is under control.