Pure single-threaded performance on an unoptimised benchmark shows that Skylake has the same sort of IPC as Broadwell. Heck, even the 3.9GHz peak clock of the Core i7-2700K Sandy Bridge processor makes it competitive here.
Remember how we tend to focus on IPC more than pure frequency alone? The Core i7-6700K 4.0GHz all-core frequency is a shade lower than the Core i7-4790K's, but performance is nearly 10 per cent higher. This is Skylake strutting its silicon stuff.
We see a near-10 per cent improvement again in the multi-threaded wPrime test. Intel's brief literature contends that Skylake is about 10 per cent faster than Haswell in well-tuned applications; our numbers tend to bear that out thus far.