AMD's Bobcat and Bulldozer

[informal]

From design to launch, a modern cpu arch is about a 5 year cycle.

BD 2 was not all around new since it's naturally based on the BD 1 version that was supposed to come out at 45nm. I suspect that like in the case of Barcelona,they were power limited at 45nm and perfromance was not up there where they wanted .So they went with an improved core,done on a smaller node and delayed it 2 years(2009->2011). This gives them more room for improvements at the core level and more clocks ,all within the same power envelope.I expect 15-20% in core level improvement + 30% in clocks.

The decode rate determines execution unit utilization

Its 4+1(branch fusion supported) decoder at the front end,with a so called "accelerate mode" if certain conditions are met.AMD is not disclosing anything about this particular feature ,but essentially this increases the decode rate by some unknown factor.