Both clock-for-clock and even more strongly for applications that can take advantage of AVX-512, Skylake can be a lot faster than either Haswell/Broadwell. Like the jump from Sandybridge/Ivybridge to Haswell/Broadwell, the jump to Skylake is a big one. For now the best comparisons are going to come from independent sources like Anandtech and hopefully from customers running their actual code on Skylake and publishing the results.