With Coffee Lake, Intel increased the number of cores in its Core i3, i5, and i7 processors by two. This marked the largest increase in core count for Intel since the introduction of the Core 2 Quad in 2006.
Core i5s now have six cores without Hyper-Threading. Coffee Lake-based Core i7s also have six cores, but with Hyper-Threading. The underlying architecture does not change from Kaby Lake. However, with more cores to share the work, performance increases markedly in threaded applications.
Coffee Lake-based Core i3 processors lack Hyper-Threading, but thanks to the increase from two to four CPU cores, the Core i3 processor family has never wielded more power. In essence, Coffee Lake Core i3 CPUs are every bit as powerful as Kaby Lake Core i5s, and potentially faster than Skylake Core i5s.