The Intel Core i7-7600U is a fast dual-core processor for notebooks based on the Kaby Lake architecture and was announced in January 2017. It integrates 2 CPU cores with Hyper-Threading support clocked at 2.8 - 3.9 GHz (2 core Turbo also 3.9 GHz). Besides two cores, the processor is also equipped with the HD Graphics 620 GPU as well as a dual-channel memory controller (DDR3L-1600/DDR4-2400). It is manufactured in a 14nm process with FinFET transistors.
Intel basically uses the same micro architecture compared to Skylake, so the per-MHz performance does not differ. The manufacturer only reworked the Speed Shift technology for faster dynamic adjustments of voltages and clocks, and the improved 14nm process allows much higher frequencies combined with better efficiency than before.
With 2.5 to 3.9 GHz, the Core i7-7600U clocks significantly higher than the old Core i7-6500U (2.5 - 3.1). That means, the i7-7600U is (at the time of announcement in beginning of 2017) the fastest dual core processor for laptops. The performance is sufficient for demanding tasks (except some games that may need four real cores).
The integrated Intel HD Graphics 620 has 24 Execution Units (similar to previous HD Graphics 520) running at 300 - 1150 MHz. The performance depends a lot on the memory configuration; it should be comparable to a dedicated Nvidia GeForce 920M in combination with fast DDR4-2133 dual-channel memory.
Contrary to Skylake, Kaby Lake now supports hardware decoding for H.265/HEVC Main 10 with a 10-bit color depth as well as Google's VP9 codec. The dual-core Kaby Lake processors, which were announced in January, should also support HDCP 2.2.
The chip is manufactured in an improved 14nm process with FinFET transistors, which improves the efficiency even further. Intel still specifies the TDP with 15 Watts, but it can also be reduced to 7.5 Watts by the notebook manufacturers (cTDP down). This will obviously affect the performance, because the Turbo Boost cannot be maintained for longer periods.