A clock speed drop must always occur whenever a CPU does more work per clock cycle, e.g. when more CPU cores are active or when wider SIMD instructions are used.

However the early generations of Intel CPUs that have implemented AVX-512 had bad clock management, which was not agile enough to lower quickly the clock frequency, i.e. the power consumption, when the temperature was too high due to higher power consumption, in order to protect the CPU. Because of that and because there are no instructions that the programmers could use to announce their intentions of using intensively wide SIMD instructions in a sequence of code, the Intel CPUs lowered the clock frequency preemptively and a lot, whenever they feared that the future instruction stream might contain 512-bit instructions that could lead to an overtemperature. The clock frequency was restored only after delays not much lower than a second. When AVX-512 instructions were executed sporadically, that could slow down any application very much.

The AMD CPUs and the newer Intel CPUs have better clock management, which reacts more quickly, so the low clock frequency during AVX-512 instruction execution is no longer a problem. A few AVX-512 instructions will not lower measurably the clock frequency, while the low clock frequency when AVX-512 instructions are executed frequently is compensated by the greater work done per clock cycle.