Intels processors are better in single theraded performance because they use speculation, a.k.a. executing unnecessary instructions (and the infrastructure required to support speculation and reordering) which also makes CPU consumes extra energy, but in many cases this is considered a worthwhile trade-off to obtain extra single-threaded performance. <br>And that speculative approach was exploited in Meltdown attack, while AMD remained unaffected, also speculative execution is why Intel CPUs always consume more power and are less power efficient in performance/power consumption domain.