SuperPi and PCMark04
According to a popular SuperPi benchmark, processors on the new Winchester core perform somewhat faster than NewCastle based ones when working at the same frequency. This is very likely to be the result of those minor optimizations in the micro-architecture of Athlon 64 core that AMD was talking about.
Similar tendency can be observed when we look at the results obtained in PCMark04. According to this benchmark, Athlon 64 3500+ on Winchester core is again faster than Athlon 64 3500+ with similar formal specifications but based on a NewCastle core. As for the performance of slower processors based on these two processor dies, we can say that Athlon 64 3200+ (Winchester) outperforms Athlon 64 3200+ for Socket 754 platform due to its dual-channel memory controller, even despite smaller L2 cache memory. The new Athlon 64 3000+ yields to a similar Socket 754 processor because of lower clock frequency.
The memory subsystem benchmark from the PCMark04 test set shows that the enhancements of the memory controller introduced in the new Winchester core are quite insignificant. The 90nm and 130nm processors are differ very slightly in performance here, with a tiny advantage demonstrated by the new Winchester core.