By sustaining single core speedups, I meant big speedups, like we were observing bin the days before mainstream CPUs resorted to multiore. It was rather more than 10%.
And we'd still have be able to make processors with lots of slow threads of course for applications where that's cost or power effective, that's comparatively very easy.
Yes, having one core at 2x clock is definitely better than having two cores at 1x clock, I'd agree with that.
These days however, the difference between fastest core performance on low-core processors and fastest core performance on high-core processors is rather a lot less than 50% (Comparing like for like, eg AMD to AMD and Intel to Intel).
